Me [23 M] with my Ex-Girlfriend [21 F] of almost 3 years recently broke up with me (not in love anymore)

Posted a while ago but got more details on why the breakup occurred. Prior to the breakup things were pretty normal, we had one hiccup on my behalf about a year into the relationship where I started to message another woman but found out quickly this wasn't what I wanted so cut off all communication, she still found out about it months down the road when she went through my phone but it was clear we had stopped talking. From that point on I always wanted to show that I wouldn't (and still haven't) do that ever again. Things were great (or so I thought) until about a few months ago when she said she wanted a break and was going to her parents for the week.

She left I cried she occasionally talked to me but not really. On the 3rd day she finally talked to me on skype and we both broke down and cried and said how much we wanted each other in our lives again. Things were pretty good for another week before I accidentally saw a message from an ex-boyfriend on her Facebook so I snooped. What I found were sexting as well as 2 nudes she had sent to this guy as well as one other she had a previous crush on. I was devastated at that point and confronted her immediately, she cried and said how we were on a break and that she didn’t do anything they were just messages. I thought back to the time I talked with the one woman and broke it off and against my better judgment I took her back and called us even on the misdeeds.

Things appeared to go back to the way they were but another week went by and I started to notice her being more distant and not as affectionate. This wasn’t completely out of the ordinary, she has depression and has gone through a few different medications and these were some of the side effects as well as a lower sex drive so I didn’t think much of it. This last week it seemed more off than usual so I decided to ask her if anything was really bothering her and that she should be completely honest with me. Without skipping a beat she turns and tells me that she was going to break up with me tonight when I got home from work (10pm) and that she would be moving out as she had found a new place already. The moving out plans fell through as funds fell through and now we are still living together but not dating and not in the same room anymore ( I have taken the bedroom and she sleeps on a mattress in the living room)

She has since told me that she had been feeling this way for the last 5 weeks now and was just not in love with me anymore, she has told me she has unresolved feelings for her first boyfriend (dated almost as long if not as long as her and I) and I don’t know how to deal with this fully yet. I have not cried about it and I don’t feel as bad as I did when I first found out but no matter what I feel I always feel this urge to have this person still in my life. She had convinced me that she was my soulmate and the person I wanted to be with the rest of my life as well as want all these things that she wanted and to show her all these things and places that she had never been before. I try to tell myself that it’s not my problem and that it’s the next guys issue to deal with all these things but I can’t help but care.

It’s not the best thing I know but I would do whatever it took for her to see that I still want her as my life partner and for her to want me back. I will move on in the meantime but what could I do if anything to get her back. I just want her to care again and it’s so hard to have all these feelings and unresolved issues with this person and knowing that none of it is going to feel better unless that person was back together with me.

tl;dr: Gf of 3 years "fell out of love" but for an old flame, don't know how to get her back or get over her.