I can't help but feel if this was the other way around, a woman who had been abused by her ex partner and was now trying to do her best in a new relationship, the emphasis would be on the new partner helping her to get through it and be stronger.
The previous response to the question should you stay together ("For your own sake and his, no.") is terrible advice. It suggests that your boyfriend hasn't fully recovered from his awful experience and therefore isn't worth anyone's time until he sorts himself out, alone. The best way to help him recover is to be in a loving relationship.
There are bumps in the road like all relationships but from your posts it sounds perfectly healthy. You had a disagreement because you he still had contact with his ex, he agreed to stop contact. Couples disagree and look at things in different ways. The strong couples work things out and stay together.
He probably does need a session with a professional counsellor to help him see how much damage the ex caused. The first step is for him to realise how much she fucked him up, the second is to move on from it.
Unfortunately, male or female, the trauma from a sustained period of abuse doesn't just stop when the relationship is ended. It lingers. I was abused by an ex during a six month relationship, I thought I was "cured" of it a few weeks and months later, but looking back I was still suffering for about seven years. I didn't seek help, which is why I am confident in my advice that your partner should.