Autistic partner - advice needed please

I have been in a relationship with my 39 year old partner for just over a year though we have been friends for around 3 years. We have fallen out over silly things in the past and he has said some things that have hurt and upset me as he has no empathy. Also, I am his first girlfriend, he has never been in a relationship before. I am very patient with him and he has shown how caring and affectionate he can be but recently we ended up having a disagreement after he had said something upsetting in a message, then the next day he said he shouldn't have said that but thought I deserved it for things I had said in the past. It escalated from there, he said he only apologised to stop me from crying, now hes not talking to me and said some nasty things to me a few nights ago over messenger. I have only ever helped him and been kind, why does he do this? My nerves are frayed and I hate the silence.