I can't relate but I sympathize Horn.
If I had a mother-in-law I wasn't fond of and a stepdaughter I didn't get along with, I think I'd have a difficult time staying sober. Strikes me as one of those things that is a constant source of stress. Have you considered walking away from the situation? Do they trigger drinking? Love the honesty by the way. And congrats on getting to day 6 (especially with the margaritas at the Mexican restaurant which you mentioned elsewhere).