Hmm, well, I became estranged from my biological father in my teens, attempted recontact in my 20s, and became estranged again very quickly. I didn't do so much as sending a letter—just a few sentences of email breaking off contact. And then I just didn't contact him. Which was easy to do because he lived on the other side of the country.

I think a big thing is ridding yourself of guilt. He was a narcissist and very skilled at convincing people that he was the sane, rational one and well-meaning. And it took a lot of time for me to understand when I was being gaslit. Reminding myself that he beat the shit out of my mom in front of me when I Was 8 and tossed the phone down the stairs when I tried to call the cops went a long way to no-contact. The estrangement was on him, even though I broke contact.

Anyway, all the luck. If I can help or you need someone to bounce things off of, I'm here.