I don't have any good advice for you.

I opened up my past due to a "fluke". I was trying to start gently. I was asking T about her values so I could guage her reaction. She refused. So I got pissed, wrote her an email telling her everything, and (in my mind) proved why she wouldn't want to help me any more. Didn't work. She didn't reject me. So I was a complete reck the next time I saw her because now she knew EVERYTHING. There was no gradually opening up

I don't suggest doing it that way though.