Why is he being allowed to take your wife anywhere? If you are married, in the US at least, you are the immediate next of kin who would make medical decisions, not him.

I doubt she is perfectly fine while living under his roof. She's likely using because he's controlling her, IMO.

Why do you need to prove your innocence? What does your wife say? It's not like you're in a court of law with him. He can accuse you all he wants, it doesn't matter. Are you still using drugs? The only thing I can think to say is that you and your wife both need to see a mental health professional, separately and together, and she likely needs to go to rehab. Going to daddy's house for a week and getting clean while he watches her every move is NOT rehab. And it's likely making her drug use worse, not better.

If you want to save your marriage, get her into rehab and get professional help for both of you. I'm sorry I can't offer other advice that's more specific but these are really issues that need to be dealt with by professionals.

I hope this helps.