I'm so sorry to hear of your situation. I know all too well the strain of caregiving and how it can destroy my family. I just posted my situation on Lisa P's thread if you would like to read, just so you know there are other families out there going through this as well.
Are you not able to see your mother? How exactly does he care for her? I'm not sure what her current state of health she's in, based on having a stroke. My grandmother has dementia, and my uncle is in just as bad health as she is from looking after her, with practically no help from his siblings. How did it get to the point where she has turned against you?
If you feel like talking, I'd be happy to listen.