I have been splitting back and forth so badly. Me and my ex partner (FP) have been living together in a house with our friends. We broke up at the end of June and still slept together for a month afterwards. All of a sudden he started getting really distant and then started being pretty shitty and shut down. I got to a point where I nearly hit him due to something I viewed as an argument but he did not. 

He now is in a relationship with someone else. We are still friends, but when he mentions her (he's bi and I'm a guy), I get super distressed and want to sabotage our friendship and their relationship.( He's apologized for hurting me and we're working things out to be on better terms. )
 
I keep going between absolutely adoring him- usually when I'm getting physical affection from him- or absolutely hating him when I'm reminded of our current standing and how he just started a new relationship two weeks after us being in a "relationship without labels" as he described it. 

I don't want to do anything shitty and I don't want to damage what friendship we still have, because I really value him as a friend. But sometimes the thoughts are overwhelming and I don't know how to shut him up, so I end up doing something small that's destructive. Which is better, but still not what I want to do. 

I haven't hurt myself, I haven't sent her a message and I haven't tried to make other people hate him. I preface any ranting about him with 'I know I'm splitting and am blaming him for everything, take what I say with a grain of salt.' 
I have been doing *okay* but it's so hard. I don't know if I have the willpower to keep it up and not break and do something shitty.