At what point do I "tell all?"

I am a college student who grew up with a Christian background, but didn't really get it until last year when I truly became a Christian. At that point, the biggest stumbling block in my relationship with God was my boyfriend, because we had slept together, and I knew that was wrong, so about a year and a half ago I broke up with him. Since then, I've grown a lot spiritually and personally, and I've had a lot of new friendships that have been a huge blessing in my life. One of these friendships with a guy friend of mine has grown quite a bit since this summer, and it's come out recently that there are mutual feelings between the two of us. However, he won't have a relationship until he and God are right, as he's working on a personal struggle of his own, which I totally understand and respect. My question is, at what point does he have the right to know that I slept w/ my ex? I feel like after his own revelation to me about his private life, he should know now, but if things don't end up working out between the two of us, I'd really rather he didn't know. But even if it doesn't work out between him and I, I'm still unsure about when it is appropriate to disclose that sort of information with someone.
Thank you