Well, I think for me, I started by sharing the small things. She handled that well and helped me navigate through all of that. Then, I hinted about some other things...I guess you could say I described an element of it but not the big picture. The things were eating away at me and ruining everything. So, one day I decided I had to tell her...needed to tell her. I called her and she had no openings. So, I had to wait several days until my next appt. at that time, I told her on the phone that I really needed to tell her something and asked her not to let me come in and not tell her, since I knew I'd be scared. Like you said, telling her did not provide complete immediate release. I was embarrassed, hyper-emotional, in utter turmoil! On a scale of 1-10, I'd give her an 11 on how she handled it. She mostly listened, empathized, showed emotion at all the right times, and asked me very few questions. Then, we began to unpack it over the next several sessions. In the end, I cannot even begin to tell you how much better I feel because I made the decision to tell her and because she handled it expertly. The combination of those two things afforded me healing I couldn't have even fathomed.
If your T handled the other thing well, I can only assume that T will handle other things well. I really encourage you to get it out there. Unfortunately it's not like you can usually wade into these sorts of things. You have to make a decision to just dive in head-first. I wrote a similar post yesterday and also added that my only regret was that I did not tell my T sooner.
I'll also add to my Ts credit, that she knew my personality and issues surrounding my image and perfectionism. She let me know that she did not think any less of me...that she thought highly of me for being able to share everything, etc.

. That meant a lot to me and went really far.
If you can't bring yourself to tell him more now, then perhaps you can start by telling him that it is hard for you to say some things because you don't want him to think poorly of you. That might be a great place to start. Good luck! I hope you can tell him soon, work through those things and find a release....