TLDR: toxic (?) ex won’t respect my boundaries to stay as friends and I feel bad about blocking him, what should I do?

For some context, this person was my first boyfriend who cheated on me and I broke up with a few years ago. He came back like last year and said he still loved me and i told him I could only be friends.

He always talked like he was mad at me for how I hurt him and broke up with him when I should have given him a chance. I still insisted that I wanted to be friends. Sometimes he would overstep and I would stop talking to him, but he’d come back and apologize. I would always be dry and barely answer and yet-

A few weeks ago he randomly called me in the middle of the night and said he wanted to marry me. I said he put me on the spot and I still don’t have those feelings.

He got VERY angry and ignored me for weeks. Every time I would say I didn’t want to be friends and it’s only me who is trying to keep this all on good terms and I put effort into the friendship, he said that suddenly he can’t tell me anything and that I make his life worse.

I really do understand that rejection is hard, but he disrespected me one too many times and talking to him gives me bad migraines and almost PTSD from our relationship and he does not respect me. I want to block him but i feel insanely guilty and just don’t want any more of his issues.