Yes, I've talked about sex with my T multiple times. I shared details as much as necessary, so sometimes it was a bit graphic, but not over the top detailed. I have one flashback with body memories of SA. I've discussed what that flashback feels like. I've discussed issues I have during sex and why those happen. We've talked about sexual experiences I had when I was young in some detail as well.
I've never talked like this with other people either, except for my partner.

As for advice on how to talk about it: 1) I think it helps to remember that my T is an adult, has kids and has (most probably) had sex. 2) He has never made it akward or even reacted to it differently than if it were another topic. Since he is relaxed and not ashamed discussing it, I feel I don't have to be either. For some reason it also helps that he's a guy.

I think as others have suggested maybe writing things down helps. When I struggle discussing something, I often also like to just say 'I'd like to share something but struggle with it'. Then we usually discuss why I find it hard and after a while of that I manage to share whatever I struggled with before.