If you can work on this with your T, at a safe place, it might lead to some real breakthroughs for both you and your partner. So there's reason to have a go.
But working through an issue doesn't have to always involve saying it out loud, and it sometimes helps to talk about "how to talk about it". With my T, some topics just weren't stuff I could sit there and have a meaningful conversation about (good sign it's stuff that needs to be dealt with!). So I'd approach the issue with my T, she'd raise a few points for me to consider, and I'd go away and write about it. Mostly I would feel comfortable enough to let her read what I'd written at the next appointment.
Oftentimes, I'd end my homework with "And I don't want to talk about this today." So we were always on the same page. And then the control of my therapy was with me. When I was ready to come back to it? I'd raise it, she'd talk, and I'd give her the heads up "I'll need to go away and write about that" when I'd reached my threshold. Rinse and repeat.
I've found that writing about stuff works for me, doesn't work for everyone though. But maybe worth a try. Maybe float a question like, "Where do you think the conversation about sex would start?" and as soon as you reach your threshold, simply "I'd like to go away and think about that..."
The point isn't necessarily to make you comfortable with sex. The point is to help you become comfortable knowing about your confort zone, how your trauma is impacting that, what thoughts and beliefs and body sensations are causing you the distress, and hopefully making it easier for you to communicate with your partner in a way that strengthens the relationship.
No need to rush this:)
