Not stealing your thunder - but I'm going through a very similar situation right now. Been with this person really on and off since 08. It's gotten to the point beyond being friends - and it sucks and hurts badly everyday. I have to figure out how to move on from my feelings, every single day. My brain is telling me to hang with friends as much as possible. I'm scared of how resentful I'm potentially becoming...
Seriously, hang in there man - we will get through it and be better on the other side!