Struggling with abusive behaviour from autistic partner

CW DOMESTIC VIOLENCE

I'm NT, I have been with my boyfriend for over 3 years, this year he was diagnosed as autistic, that's been a huge relief for him.

At the beginning of our relationship he showered me with love and compliments, now affection is very rare, he puts me down constantly

I'm trying my best to learn and be accepting, if he seems short or rude or judgemental I understand a lot of the time is misunderstanding or miss communication.

Once we started living together he occasionally has really angry outbursts, maybe one every couple of months. what would start as just a small argument he would quickly escilate by screaming at me. they started as just shouting, then hitting/throwing things, hitting himself and telling me it was my fault, chasing me. Last year was the first time he threatened to kill me when he was angry. More recently he has actually hit me then yesterday I woke up in a bad mood, so did he, when I talked back to him he just lost it, he started screaming that he would kill me and chased me, he grabbed me by my hair and scratched my face up. 

Once he has calmed down he says how sorry he is, and that he just gets overstimulated and can't control his anger. He accepts that what he has done is wrong but I also feel like he has an attitude of 'you don't understand because you're NT' or that it's my fault for talking back or prevoking him or that he isn't an abuser because he is autistic. 

I don't know what to do, I haven't told anyone. I still love him and I want to understand and help but this is just getting worse and I don't feel safe anymore.