Why can't I get my ex off of my mind?

I was dating a girl that I was absolutely in LOVE with. We had known each other for about two months before we started dating, but I should also mention that every chance we got to hang out since that day we met we did. Literally every chance we got. We started dating after a night when she was acting very... show more I was dating a girl that I was absolutely in LOVE with. We had known each other for about two months before we started dating, but I should also mention that every chance we got to hang out since that day we met we did. Literally every chance we got. We started dating after a night when she was acting very depressed at a buddy's house for a campfire. The entire night we did nothing but sit by ourselves up in a treehouse and talk, and talk, and talk some more. We got to know each other exceptionally well over the two months we had known each other so just sitting there talking for hours wasn't much of a stretch for us. I had feelings for her long before this particular night but this was the first time she showed she had feelings for me as well and the first time I really showed her I had feelings for her. I had asked her out the next day and she said yes (obviously). We got along exceptionally for 3 1/2 months then she called me and sounded super upset about something. She finally spilled that somebody was making up rumors that I had gotten her pregnant which very much bothered her because everybody had called her a slut, whore, *****, and so on and so forth her entire life, and it made it worse because we had literally had NO sexual contact at all. Hard to believe considering I was a 21 year old guy dating a class-A hottie, I know, but I didn't look at her as a piece of meat, she was my girlfriend that I was absolutely in love with and that I would do anything for. We ended up breaking up for awhile to let the rumors and gossip simmer down a bit. Something happened, that I don't feel I should disclose here, that kept us from contacting each other for a couple of months. When we finally re-established contact she acted like she couldn't care less about me, although I could tell she did and I definitely still cared about her. The problem with this though is that she had a new boyfriend, or rather, a new old boyfriend. We've only seen each other once since the breakup but that was a LONG while ago, I haven't talked to her in a good 6 months because I lost her number thanks to breaking my phone and I had to get a new number, also thanks to breaking my phone. Next month it's going to be one year since our breakup and literally everyday I think about her and how much I wish I could be with her. I know it sounds like I'm crazy and obsessed but I have honestly tried everything to get her off my mind, I've even dated a few girls since then but those relationships ended with the girls telling me that they just don't have feelings for me. I just CAN'T forget my ex. She is the first person I've had this problem with and my friends are little to no help at all, they all tell me I should get her back because we were perfect for each other, as you can imagine, that is NO help at all. I do still love her but I'm trying my damndest to move on and I keep running into the wall of memories with her. I feel as though this isn't a problem that I can fix. Any help or suggestions on this matter would be greatly appreciated.
Update: Update: She called me tonight (2/15), we talked for an hour and then I had to go because I was going in to a job interview. She didn't want me to go and we had been talking for an hour. And another thing, she had to call me restricted because she can only talk to me behind her boyfriends back and didn't... show more Update: She called me tonight (2/15), we talked for an hour and then I had to go because I was going in to a job interview. She didn't want me to go and we had been talking for an hour. And another thing, she had to call me restricted because she can only talk to me behind her boyfriends back and didn't want me accidentally calling her or texting her. We talked like we had never stopped talking. As you can well imagine, I am now very confused.
Update 2: Date is wrong in last update, it was Valentines Day, the 14th
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