is forgiveness possible?

You need to sleep with her mom. Also.

I've never had an issue with forgiving ex's. People make mistakes, they're flawed, monogamy is hard, etc. 
 
That said, I don't forget. Hurt me once, shame on you. Hurt me twice, I'm a stupid bastard.

My brother cheated on his fiance when he was drunk and accidentally made a baby and they are still friends.

Giant Bomb is so fucking weird.

I wrote this rambling account of my experiences. Then I deleted it. No one wants to read that shit.

TL;DR. Here's the short version: there is a reason your relationship went south and, more likely than not, it still exists. So it goes.

Anger, jealously, all of that fun stuff is fueled by your own ego.

Honestly, not to sound too blunt, sometimes you just have to get over yourself. Many relationships will come and go through out life. It's purely up to you how you react when things don't go to plan. Take these kind of experiences as life lessons that help develop your character and mature you as an individual. All of it helps you grow in the end. Life's good man, it's just not always roses.

Me and my ex recently forgave each other for pretty much being shit boyfriends and girlfriends during our relationship. Hell I forgave her for when she broke into my house, stole items, set said items on fire, and then gave me back the ashes.
 
If you can forgive someone for that I'm pretty sure you can forgive anyone. It's all just a matter of time.