<human>: Can you provide a brief rundown of the text in within 3 sentences?

I spent three months with a girl I fell head over heels for - she was the best girlfriend I ever had, we were really serious, we had sex almost every day. I'd never been as happy as I was for those couple months. She was severely bipolar and took tons and tons of meds (benzos, antidepressants, etc) but I always told her I didn't care and that I would stay by her side no matter what. She said I was the most supportive boyfriend she'd ever had.

Well, as you do with good girlfriends, I introduced her to all my friends, we were all a big happy family. There was one night that I stayed up into the wee hours of the morning talking with a friend of mine (let's call him Jack) about the relationship - just asking for advice, he recently had his fiancee leave him and we had a heart to heart. Right around that time, my girlfriend started talking to Jack a lot more, and pretty soon was becoming really distant. 

Seemingly out of nowhere, she dumped me saying I just wasn't her type. Next day, I see her with Jack and drama ensues. I found out that they fucked just a few hours after she dumped me, and were now in their own relationship. Same fucking day.

Here's the good part: Jack (who I was tight with for three years) is the roommate of my two best friends and shares most of the same social circle that I do. So all the rest of our friends are also caught up in the drama and no contact is pretty much out of the question unless I stop hanging out with all of my friends.

It's been almost a month and the wound is still fresh. I felt so betrayed and confused. I have been doing my best to maintain my dignity and put it behind me, but fuck if it's not near impossible. Saw them for the first time at a party last night. I didn't start anything but you bet your ass I made some passive aggressive drink raises (maybe unwise but whatever) and wept like a sack of shit when I got home.

So the whole thing is a giant mess for me. If anyone out there has been through something like this or has any advice that would really be great.
<bot>: girl I was crazy for left me for my friend under suspicious circumstances, now I am left to deal with the emotional and social carnage.