TW (sa)- need advice to improve sex

I’m in a relationship with a man who’s perfect in every aspect. The only thing wrong in our relationship is I can’t bring myself to have sex with him. 5 years ago I was SA’ed and since sex has become something that freaks me out. I don’t feel like I go into a panic or feel fear, nothing like that. I just get very tense and start overthinking, like “what if I get flashbacks and start panicking”.

I’ve already had a discussion with him about this and he’s reassured me that it’s completely fine, he understands and will wait years if that’s what I need. But I do want to have sex with him.

I need advice on how to stay in the moment leading up to and during sex. We’ve gotten close a few times but each time once he starts touching me down there I get tense and go dry. I know it’s not a medical issue because 1. Everything’s good as it should be on paper 2. When we have to stop for an unrelated reason or if we accidentally ramp up to that moment but have to leave I stay wet and turned on.

I already know I feel better with the lights off and with background noise, but other than that does anyone have tips for staying in the moment?