How can she move on so fast after 2 years with me?

I had to come and discuss this with someone, me and her broke up in December, together for 2 years. She had been checking my socials after that and messaging me about women liking my stuff and following me, I told her I wanted her back and she said she wants me but she can’t, anyways time goes by and we in January, met her to give her her keys back and she breaks down about being in love with me still but because of the history we had and me messing with someone during the BREAK we had which was her choice btw, she can’t be with me. I still haven’t seen anyone or met with anyone, I sent her flowers Valentine’s Day as we were still talking and she said thank you their beautiful and how she still loves me and cares for me but wants me to leave it. She had me blocked on all socials however kept unblocking me to see what I was doing, 1st March she messages my boy to ask if I’m okay because she saw on my Twitter that I had got into a fight, my boy tells her to speak to me and she says “I can’t open up any communication with him” just Sunday gone (Sunday 8th March) she tweets about having how cute a guy looks when they’re snoring, I completely lost it man and I went to her house and the guy was there, he tells me to move on she doesn’t want you anymore and I say to him it’s between me and her but she had been communicating that she still loves me and cares for me and how there’s literally no one else she wants Valentine’s Day, turns out they had been seeing each other for 3+ weeks so why was she so into my business? Why tell me u still love me? She then comes out on the balcony (I’m guessing she was naked because it took her a while to come out) and tells me she doesn’t love me anymore and then later that day tells my boy that she’s sick of me and she wants to be left alone because she’s happy. All my friends think it’s a terrible rebound and she just sticking with it until she’s over me, when I told the guy she’s with now how she had been emailing me, he had no idea about it. She really played games with my head & I can’t believe it man. What do you guys think? Why did she tell me she would be hurt if I had moved on? She had been asking me about posts literally under a month ago, has she really moved on or she just trying to forget about me?