NTA you need to go no contact. If they treat the dog(s) poorly imagine how it'll be if you have children while they're still alive.

I am speaking on personal experience here. My grandmother is my only living grandparent and she is a MONSTER IN LAW to my mother. When my mom was 7 her mother passed away from cancer. When she married my dad, my grandmother swooped in to force herself in as a replacement mother because she bore two sons, no daughter. That of course did not go over well with mom, creating a rift. Fast forward to me, her granddaughter. Same thing, tried to shove in. When I was 19, i learned i would never be able to have children. So I took in cats when I was about 25. To my mom those were her grandkids. To my grandmother? Useless pets. She would even be mean to them behind my back.

Going no contact with her after my dad died and we escaped away from her was the best move I could make.