re: speaking to him again
It's absolutely up to you. Is your choice to decide what would be in best for you emotionally. If you have a current T it might be helpful to get their perspective, or a trusted friend who knows about the situation and knows you well enough to have some insight that we might not know enough to have.
That being said, if you think it would do more harm than good for you, it is absolutely not your obligation to do so, and protecting your own emotional wellbeing is the most important thing.

I can speak about my own experience. I waited ten years to write my old therapist. I first had the urge to do after a few years when I was quite angry and I wanted to let her know how much she had screwed up.
But I knew that if she tried gaslighting me that I would start to question myself and there were a lot of potential responses that would have hurt me again.
So I didn't. I wrote quite a few angry letters over the years that I never intended to send, but that was for myself.
It wasn't until after ten years that I felt ready. I felt ready when I knew she didn't have power over me anymore. I waited until I didn't care whether she responded or what she responded. Then I sent it for me, not for her.
I got a reply and didn't open it for almost six months. Because I didn't actually care what she had to say. I didn't need to know whether or not she was sorry, because I knew she was in the wrong and an apology or a defensive response didn't matter to me.
I recently opened it only because I wanted to contact her again to ask for records that would help me remember things for my current therapy.
Turns out the response was something that would have been incredibly invalidating and harmful for me to read five years ago. And I didn't care. I just responded to ask her for the records and didn't feel any need to insist that she acknowledge what she'd done. I just want my records.

None of that is to say you should or shouldn't contact him. Just wanted to throw it out there in case it's a perspective you can relate to and would find useful.