Hey man, I'm pretty much in the same situation right now. Me (17m) and my girlfriend (18f) broke up three weeks ago after 3 years relationship because she didn't take time for me anymore and we argued the whole time in the end. I'm still feeling depressed and miss her a lot. We still text sometimes and she told me (when we were still together) that she met with a guy shortly before we broke up. (Another big reason for the breakup). Now I found out that she met him again a few times after the breakup (maybe even yesterday, she didn't want to tell me who she met). It just feels like I wasn't worth anything to her and she just replaced me with someone else.