Share with him as much as you are comfortable with. There is no set of rules for this sort of thing. While I haven't experienced life long trauma, I was abused and I started slowly and then kind of brain dumped a lot on my t in written form. But if your comfortable sharing more now, than do it! He's not going to think your crazy for sharing what you perceive as so much so soon, he'll think your brave for being able to do that. (but paradoxilly he's not going to think your not brave if you don't)