Maybe you could write on the computer such as on a website or a word document, instead of on paper? That way he can't go through it. I really hate privacy invasion, so I can see how that is a really stressful and isolating situation to be in. I understand not being able to go to him about your relapse. Is there another person you trust that would not tell your family, or someone that doesn't know your family at all? If you're feeling lost on how to deal with it, then maybe going to someone you trust for support and advice will help you figure things out. The best case would be to go to a therapist, but if your family doesn't know, then it might be hard/impossible to hide that you're going to see one.