You shouldn't feel ashamed about talking about your experiences and how they've shaped you. If he's a good guy, then he'll understand and support you. I think it'll draw you two both closer, but also don't feel the need to talk about it before you feel ready. You don't have to give details either, just the general gist of what you've endured. Honestly, you don't have to tell him at all! It's totally your choice, but I don't think you have anything to lose and I think all of us on the board would understand your decision no matter what it is.