Cannot communicate with bipolar 2 partner

I'm very new to this so apologies if this is long and boring.

My partner was recently diagnosed with bipolar 2 after years of trying to get help. He was variously treated for depression, ed, alcoholism and anxiety before finally we got to the actual problem.

In some ways this is a massive relief. At last! A reason for all these horrible mood swings and ragefits. He began treatment, mood stabilisers and therapy and for a brief moment I really thought "great, now we can start to be happy".

It was naive, obviously, to think this way and I know this is going to be a long, long process with many slips along the way. But my god, I never thought it would be this hard.

I love my partner. I wouldn't still be with him if I didn't, but I feel completely trapped and controlled within the relationship. Everything I say to him is analysed, scrutinised for criticism and thrown back at me. Asking him to do anything at all, questioning anything he says, even just having a very slightly different opinion on something, results in slammed doors, screaming abuse and threatening to leave me.

I am the enemy. I am out to get him, out to control him, and somehow completely responsible for every argument.

I bear my share of the responsibility, I have learnt since his diagnosis that the worst thing you can do when a bp person is flying off the handle is argue back. But it is so hard when you don't understand why the person is angry in the first place, and when all you want to do is fix it and make it better between you.

My natural instinct is to try to calm the situation and explain how I feel, but this is just like painting a target on my head and saying "go ahead, take a shot" to him.

I know I need to walk away in these situations, and I'm getting better at doing that, but surely he needs to take some responsibility for his own behaviour too?

In the heat of the moment, I can understand why it would be hard to step back and get perspective, (as I said, I am just as guilty of this sometimes), but I would say 70-80% of our rows are over literally nothing. (A look, my perceived "attitude" towards him, what he thinks I think about him etc). Surely after the event, in the cold light of day, he knows he should apologise or at least take some responsibility for his behaviour?

Right now he is stomping around upstairs fuming at me because... I really don't know. I asked twice what I had done and this just resulted in him completely losing it. It's so hurtful and unnecessary. The names he calls me, the things he says, are totally out of proportion in relation to what has actually taken place. At some point today he will probably start being nice to me again but I won't know why and he won't explain his reaction, this much I know.

I am so proud of how far he has come. He has been so brave and worked so hard, I really don't want to rain on his parade. But I don't think I can spend the rest of my life being his verbal punch-bag either. It's a truly awful feeling to have someone you adore daily telling you why they hate you. I would appreciate any perspectives on this, I really need help.