NTA. Stop trying to prove yourself to this woman. She isn't your blood. She married your brother. Any efforts to prove your sobriety to her has only empowered her thought process that she is entitled to your personal information, health information, right to privacy. Your folks and brother really need to have a discussion with her about personal space and boundaries. She's way out of line here and unfortunately you have allowed that line to become blurry. For future reference, never discuss your sobriety or anything personal with her ever again as she is carrying herself as the matriarch of your family. Don't apologies, don't explain yourself. Don't discuss anything about yourself with her ever again. Things need to change asap, reclaim your life, you earned it!