Was my ex already talking to someone which was the real reason for leaving me?

So my girlfriend had recently broke up with me, she literally had no real good reasoning and literally packed up and bounced out. No I will explain what events have led up to all of this happening but still she has no real good reasoning to do what she has been doing to me and I just need help with understanding everything as well as trying to getting her back please.
No I left New Mexico and moved to Illinois to be with this woman I don't know anyone else around here just her all my family live in California and New Mexico and I am not close to anybody at all I don't have any good friends and my family are all tough love type people they don't like drama nor hearing it so if you have it keep it to yourself basically. I do have kids that live with their mom in New Mexico which I pay $650 a month in child support and have not missed a single payment but I rarely ever get any time with my kids due to the fact that their mother is super greedy with them and uses them to her advantage with me and yes it sucks. And yes I know what steps I need to start taking in order to get my fair share of custody which I'm in the process of doing I'm just waiting for my emotion to go through and getting my court date to get in front of the judge finally anyways I've moved away from the ones I love the most and care for the most so that I can be with this woman that I've known now for now going on 4 years. We tried dating when we first met and trying a long distance relationship but of course it did not work and she ended up getting with someone else and even though I asked her to come out to New Mexico and get me she chose not to and instead actually started talking to someone else who is awesome in New Mexico and she ended up coming all the way out here and getting him and running off and actually marrying this piece of **** who turned out to be an ultimate piece of **** beat the ******* living **** out of her and she actually stayed with this dirt ball for six months before he was finally arrested and sentenced the prison for 2 years for his abuse she finally was able to get her divorce from him just a couple years ago. And then she got with another guy who was another piece of **** he didn't work he lived off of her who may I add is a nurse that has been a nurse for 13 years long and going strong who makes very good money and does a very good job at what she does but this dirt ball tried living off of her and his hobby was selling Hot Wheels to make his part of income to pitch in which was absolutely not cutting it and she finally got tired of it after too long years with this ******* piece of **** also not only cheated on her twice but also put his hands on her at one point he even threw her under the bus when they were drunk one night and he was behind the wheel and ended up crashing their car and when the cops arrived he immediately told them that she was the driver and got her charged with a DUI which she was still fighting when I finally got my opportunity to be with her and moved up here and actually helped her get out of it by giving her better advice than her public defender was giving because I am actually a very knowledgeable in fighting court cases which she ended up getting the charges dropped because of me. So anyways I moved out here back in March in order to be with her and to better myself by getting away from the life that I was living in New Mexico which was constant drug use and not living a life that I should be living especially being 100% disabled veteran. Now the fact that I moved up here not only to better myself and to get on a path of sobriety but I also wanted to be in this relationship I wanted three long years ago and I finally am getting that chance. So after living with her in her own apartment for 3 months we moved to a new city which right before moving we got into a huge heated argument and I ended up leaving and driving all the way back to New Mexico because I thought we were for sure done for but once I was in New Mexico she called me and she actually thought that I didn't even leave and was telling me to come back which I freaked out and was like what the **** and I actually hung out for 2 days with my kids before driving all the way back and actually putting paperwork in to buy a house and getting approved for it in the city we we're having to move to so that her oldest can attend college there for scholarship he had. Now I got this house in my own name because her credit was not allowing her to be on the paperwork but we were cool with that especially the fact that I was finally doing something I wished I done years ago. And finally getting the opportunity to show her that I am here for the long run and I'm not going anywhere and only here to support her and her family as much as I possibly can. Now I will say that due to the fact that I had to spend that money driving to New Mexico and back for absolutely no reason set me back and I actually had to ask her to help me with paying the down payment for the house which she was not too happy about and has brought that up many of times every time we get into a argument, after living here for a month and a half we ended up getting into a huge argument with which included her son and her son's best friend who also lived with us who's mother also was involved because I had actually was trying to talk to this woman and trying to get her to meet me in person so that she could at least get to know who's her son was living with and for her not to get any wrong impressions and that's all my intentions were with talking with her and it was all through text messages and never once did I meet up with this woman not once in person but due to the fact that it was a huge heated argument that night those kids decided to blackmail me and try to make it seem as if I was trying to hook up with that kid's mom through text messages and told my girlfriend all this crap and that woman actually sent her a text messages that were sent by me to only show that I was trying to hit on her in some way but I was only being nice to the woman not trying to hook up with her and that caused my girlfriend to freak out and not just break up with me and leave me but to try and humiliate and embarrass me to everyone and anyone possible telling everyone she can that I am a heroin addict and a loser. she also went as far as getting me in trouble with the law and calling the police on me and telling them that I had drugs on me and that I was a drug addict. She literally told my neighbors that I haven't even got to meet completely yet that they need to be careful with who they're living by now because I am a jackass heroin addict that can possibly steal from them but that is far from the truth because I left the life behind me months ago and she knows it and I've been on a path to sobriety and bettering my life not just for her and myself but for my kids. And I don't work because I'm 100% disabled veteran and don't need to and the fact that she is a nurse from 9:00 to 5:00 Monday through Friday I am at home everyday while she is at work and never once since I've moved in with her have I ever went out on my own or going to do anything without her literally even if she told me I could I still just couldn't I don't like doing nothing without her and due to my PTSD I just don't like being out and about at all really and without her with me I just don't feel comfortable at all and she knows this as well. I have absolutely no intentions of ever hurting her in any way and I know what she's been through in her past relationships and she has been treated like dirt and I want nothing but to give her the best that I possibly can. I had I too have been in shitty relationships all before this and all girls that I've been with had no interest in my feelings or well-being and only wanted to be with me for what I had and for what I could give them. But all I want is for the best and to give my all for this woman. And honestly along with buying this house which I've never done before and the stress of fixing it up and living in this town that is literally 10 times smaller than any City that I am familiar with has really brought out my anxiety and depression. So this cause has caused me to not really be expressive about my feelings towards her and I'm not able to even talk as much as she probably wants me to and has gotten vibes that I am not interested in her at all but that is not it at all and I have let her know that several times but still she continues to say things like that that I am not into her and that I am showing her signs that I am not interested in the relationship. No due to the fact that she really thinks that I had plans on trying to hook up with that woman who might I add is over the age of 40 super skinny and gross looking which is also known for being a homewrecker in three other relationships and there is no way I had any interest in ever doing anything with her all I wanted was for the best in her kid and her kids friend and to show her kids friend's mom that I'm not a bad guy and she needs to know who her son is even staying with since it is my house that he is living in that is all my intentions I had. No I am asking why has my girlfriend not only broken up with me because of my actions of talking to that woman through text messaging and what I had said which had absolutely no sexual talk or anything of that sort the only thing was I was being extra nice like telling her that I would take her out and get her nails done and just chilling out showing her that I'm a good guy is all I pretty much said. But for her to go as far as breaking up with me even though I haven't even done anything absolutely wrong to her like hitting her or cheating on her or mistreating her in any type of way or going behind her back and doing anything of that nature she still breaks up with me and leaves me when I bought this house for her and was here for her. And then to top it all off she goes as far as doing whatever she can to humiliate me and embarrass me in front of her friends and in front of people I don't even know and knowing the fact that I am miles away from anyone I know or anyone close to me really sucks and I literally don't know anyone around here at all and now I'm here all alone and do not know what to do can someone please help me with not just figuring out why she left me and was it because she was talking to someone behind my back and I just gave her extra reasons to move forward with her relationship she was having on the DL and also advice on what to say to her to get her to come back to me by the way she has blocked me from any type of contact except for Snapchat thank you for reading and taking the time to help me out