NTA at all.

You told her in confidence, it's not his business. She shouldn't have said anything. The only thing this is going to do is push you away.

But, despite her being totally TA, I will say this: i went to rehab 10+ years ago and my family STILL questions me from time to time. Most recently last month - my parents were worried that i was "distancing" myself from the family... I was working 65+ hours a week. I wouldn't have TIME or ENERGY to relapse. We're short handed, and i love my job. Unfortunately, when you've broken the trust, and people who love you have genuinely been worried for your life, I don't think that worry ever truly goes away.

Again, this is a private matter. She is TA. You don't have to put up with it. I certainly don't appreciate my family's behavior, it's beyond frustrating and at this point just pisses me off. But in some situations, it's going to happen.