I am not-my-probleming my dad onto his own family when he gets to this point for many of the reasons the LW has drawn her line in the sand.

So, no advice from me but I very much wish that LW's wife was capable of telling her racist, homophobic mom that mom doesn't get a choice and will be moving into a nursing home whether she likes it or not. (Tbqh Wifeo should have been preparing for this, including therapeutic work, for years, and so I have no problem calling her spineless (if there's no large inheritance at stake) and/or golddigging (if an unmentioned inheritance is adjacent to/the reason she's insisting on being her mom's caretaker.)