I have to agree with what others have said here. The diagnosis doesn't excuse the behavior. It explains it but doesn't excuse it.

I was just reading about autistic conditions in a book the other day. It said that the way the brain of someone with such a condition works is that they have a hard time empathizing with others and essentially see people as objects, no different from a table or chair. This isn't because they're evil or anything. It's just the way their brain works.

The book also talked about how some people with high-functioning autism can understand what empathy is when you talk to them about it, but when it comes to following through on that knowledge, they can't make the connection between what they know intellectually and what they're experiencing in a real-life situation. So when you alert him to the fact that he wasn't taking your feelings into consideration, he may intellectually understand that and feel sorry, but that doesn't mean he can actually put himself in your place and understand the pain you're experiencing. (Hope that makes sense.)

The fact is that we sexual abuse survivors need sensitivity. We must be with someone who can empathize with what we feel. If the person we're with has some condition that prevents this (and there are, sadly, a number of different ones, not just autism) then we need to seriously consider not being with that person, no matter how much we care for them and how much they care for us. It's painful, but it's the way it is.

If you're afraid of him then that's a major red flag. Plenty of abusers, for instance, apologize profusely every time they abuse, but it doesn't stop them from abusing. If he can't empathize with your experience, he may well continue to assault you (and it IS assault!). There are times when we just need to accept that a situation is nobody's fault and protect ourselves.