engaged and broke up by her mother

We were friends from high school .
we talked about dating while back but i wasn't into her at that time.
after service in the army we started getting out again and than we came to be together. her mother didnt like me from the start. and from the start we were hiding our relationship. also she is very very religious mostly cuz of her mother, her mother started being religious when her husband died.
and pretty much force it on my ex and her little brother.
when we started dating my ex had many conflicts about us being together cuz iam not a religious guy at all, i almost hate it , but i did love her so i was willing to try and do my best for her. and so on our time together keep on going and few months later we told her mother about us. and she wasnt all happy. her mother started making her feel uncomfortable That she's dating a non-religious guy, at that time i wasnt looking much religious.
her mother even kicked me from their house once with an excuse that the neighbors are talking and it's wrong for a religious girl to date someone who is not religious. (and her neighbors are not religious ) so i knew it was a bluff just to make my ex feel unwell .. she always playing on her mind like that.
time pass and i proved my self of getting more into the religion just to make her feel good while i hated most of it , not all but most.
her mother seems to calm and more or less accept me.
after the first year together we talked about getting married , we knew each other for 8 years from high school, and she was very unhappy to be with someone while not married always felt dirty doing things in bed without marriage, we did it few times and she always felt a shamed after it.
we did try to stop but it was stronger then us. than i went and got her an engagement ring , asked her mother to permission to marry her daughter (she got no dad so i asked her mother ) she agreed. i was thinking things going to be better and maybe she isnt so bad. but it wasnt . after we were engaged not long after .. her mother started dating a guy that came from Ukraine (same as her) he isnt religious of course. but she didnt care.
just 3 months after they started dating she declare that they are gonna marry, she of course accepted him without being religious.
i didnt care much about them i was more focus on my ex and my college studies, but i was feeling unwell about this... remember she did a lot of preaching cuz of that im not religious, and now this.
my ex become more and more distance from that point.. i felt like things getting out of hand. her mother started going with her and her new boyfirend with her daughter and his son. but it was fine.. ,skip few months a head around 1 year and 9 months things started getting less and less nice .. more fights over small things, every little thing set my ex off.
we had up and downs and always felt its coming from her mother, cuz my ex always told after she was made at me she said "my mother was right"
and "my mother knows best " we were closing in to our wedding date, we set 1 year from that engagement we did ,my ex started saying things lets wait .. im not sure.. i was scared to lose her so i asked what the problem she started saying her mother think she is too young to marry and such (she was 22 at that time and i 23) we talked about it few times and as she started crying over it i asked her if she wants us to marry lets do it if not lets stop it , she said "lets wait another year" and i told her that i feel like she wants the way out , and in of this we said lets keep going and we went to buy her a wedding dress , as her mother started going with her to the wedding dress women that make the dress she always came more and more sad. i was feeling as if she wanted to leave me , and i was getting more and more suspicious.. i asked her if she want to leave me and if not what is the problem.. but she said no i love u i want us to keep being together and such.
but she was deleting msgs on her phone (nothing was there ,every time we sit together even if i blink to her side of the phone she would tell me that i Invades her privacy, and she was sitting next to me i couldnt not see while she text just on the side of me .. but i wasnt looking i truly couldnt see anything i just saw her delete everything ... convestion from any one, just a blank phone. it was the 2 years of our Relationships. i made her chocolate heart cake , and we went to eat at a restaurant nothing felt more .. dry, hard to say we were happy. i tried to talked to her about it few times but she was just getting close more and more. never straight answer. after this not long time maybe a month or less i saw a new laptop at her Living room were we usually sit to watch movies. and this laptop is open in front of us, so i" oh nice new laptop ? "as i just looked at it she started getting angry at me and tell me its not of my business and to stop looking on it and being nosy.
as i asked her of who is belong to ? it was clear to anyone it wasnt her, nor anyone i know, i could tell it had fallout 4 on that laptop (that gave me 2 hints 1. this is strong laptop to run that new game so its expensive laptop 2. its not belong to and old guy. as she didnt gave me the answer right away. later that day she gave me the name of the boyfriend of her mother. for a moment i believed it is ,maybe it is his son game and such , but i couldn't be more wrong. not long after she broke up with me she came to my house giving me the engagement ring and all the jewelry i gave her , all inside a plastic bag as didnt say a word and got back to her mother car and they two drive off . i tried to talk to her explaining why , she wasnt willing to talk.
her mother told me its over and not come or talk to her daughter anymore.
a day after we did talk , we both were crying but nothing was clear why.
why exactly we stop, she said we dont love each other anymore and thats it.
i tried to fight for our Relationships and maybe getting some answers .
cuz i felt there is more to this, as i started opening Instagram for the first time only after a friend told me to check out her Instagram to get there some answers, i saw it .there she upload a photos of being in places such as restaurants and all and such. just the place itself never her with anyone, i was new to Instagram but i suddenly i saw it that i can see exactly her last likes and comments she did on photos (at that time u could see that )
i saw her chatting with a guy, that not long after it was known to me they are together.