I tell them about it when I am ready. Most men are very supportive and understanding. But if you do suffer from PTSD where the point that you fear intimacy, the best point is to seek help from a counselor of sorts. It took me awhile and everyone reacts differently to trauma which is why individual care is necessary. Its been years and I still suffer PTSD but when I am with a partner that I trust and care about I don't have any issues with intimacy at all.