From my own experience, I would encourage you to be as open with your T about other traumas as you feel able to, when you're ready to. I suspect that you might actually be there now, because you're thinking about it in the way that you are. The reason why I say this is because I have found that multiple traumas all relate to one another in sometimes odd and subtle ways, and that they can be a sort of integrated whole at some level. I think that the way we experience and make sense of and process trauma is very much affected by prior traumas, one defines the other. It has just been useful to me to look at things side by side, both intentionally and not.

What your question also trips for me is that sense of "what's there really to be sorry about" with respect to being open about things in therapy. Do people really feel bad that they shared "too much" in therapy-- outside of all the pretzel twisting that naturally comes with it, such as now my T will hate me, think I am a terrible person, yadda yadda? At the end of my life, I can't imagine saying "I shouldn't have said so much in therapy." That would be like saying, "I shouldn't have spent so much time with my child." In the bigger picture of things, not just about one decision, I suppose I would rather err on the side of being open than closed.