Theraoy for relationship issues

I'm feeling really hurt right now. To type the whole story out would be a lot but this is the gist.

I found out my bf had been on online dating sites. After confronting him I found out two more times after. He didn't meet anyone and barley spoke. Apparently was there out of curiosity and also from drinking binges because of issues with ptsd.

Since then I have distanced myself from him emotionally and physically. It's not on purpose it's like automatic and I can't help it. Which I feel is normal.

Just to add here please no comments on just leaving him. Its not possible right now or anytime soon.

Last night I mentioned I felt distant and that I needed to be in order to protect my heart.

He said today he felt upset by that. I explained in detail why this was happening. Rather than him being understanding or taking responsibility he just said. "You should go to therapy."

He didn't say we should..... No only I should. I've asked him for couples therapy too and he said I should look for it not him. He caused this shit I feel like he should be the one working hardest to fix it.

I'm pissed, sad and frustrated. I don't know if I'm looking for advice or just need to vent. I put so much effort into this relationship. We live together so it's not look like I can get away for a while.