Stepdad

My mom met my step father when she was 30, he was her manager at work and was 55. He helped us get away from my abusive dad, and then began to date my mom saying she owes him. So fast forward to an out of state move, followed by him moving in with us. A horrible childhood, him threating, starving and verbally and emotionally abusing us. 20 years later he is now 75 and my mom 50, he has had two strokes and a heart attack. I became his caregiver and rhe abuse got worse and worse, finally he cussed me and my mom out one last time and she finally had enough. She told him she is divorcing him and that he is going back to his home state and is going to a living facility. His daughters are involved with helping find a place. He keeps saying hes loosing his family but hes not. He is extremely abusive and controling, he yells and threatens us, he is mean to the animals. Is it wrong to leave him even if he is in bad health? And also does anyone have advice on how to afford assisted living? He only gets 1900 with ssi and he doesnt have a 401k, life insurance, or savings. He told my mom that he needs a lawyer so he can get alimony and not get screwed over in this divorce like the last ones he has had. Btw this is his 6th divorce