It’s a ‘blip’ if it’s once, say in a social situation, and he regretted it, spoke about it and wants to move on. Relapses happen
If you believe that then you need to accept it and move on
It’s extremely hard not to get angry when you feel betrayed and he needs to understand that he did that, not you
You need to think about your boundaries and set some. What is making you anxious or uncomfortable? What does he need to do to build the trust back up? Sit and discuss it and ensure he knows you want to support him but you also need to look out for yourself