SUBREDDIT: r/relationships
TITLE: Me [19 M] and my girlfriend of 3 years [19 F] just told me, at a club, that she's been hooking up with one of my childhood friends. Just got home. Can't sleep. How do you guys even deal with this shit?
POST: Wow. I feel like total shit. This girl was, what I think, the love of my life. While our relationship had it's bumps and bends, I thought people had a little bit of decency. He's been one of my good friends since middle school. I've had a gut feeling about this for so long, it's just that she always reassured me nothing would ever happen. Man, do I feel small, and like such an idiot for letting myself get dragged around like this.

 My brain is telling me this is good, but the rest of me feels like total shit. I hope I'll never have to feel this again. This fucking sucks. I'm laying here, trying to sleep, think about other things or get over her but I can't. And it seems like most of my friends don't really mind/say anything (me, my ex and "friend" have all been in the same social circle for years now.) How do you guys deal with this stuff?
TL;DR: 
Long term girlfriend (ex-girlfriend) told me tonight that she's been hooking up with my childhood friend. Just need a little help coping with the situation. I feel fucking small and alone.