Two things - like everyone said - do not go off your meds. They are the thing giving you any recovery and functionality you do have. And YOU know your history, you have lived it, no-one else. Trust that knowledge and your gut.

Secondly, this is a really fantastic opportunity to start to learn assertiveness skills and boundaries, boundaries, boundaries. I would work with your therapist to really focus on those things. The obvious starting point is with you father in law, but these skills will serve you well in all areas of your life going forward.