Mother-in-law is mentally unwell and can't afford her house. Advice?

My mother-in-law has a history of mental illness. Truth be told, it had a very large and negative impact on my husband throughout childhood and teenage years. She has a pattern: work becomes "overwhelming" and she stops going. She becomes paranoid about people coming into her house. She isolates herself and starts turning off services (phone, TV, etc.) to lower her bills. Eventually she is institutionalized against her will. All of these times, she has had a boyfriend to financially take care of things.

Fast forward to present day. My mother-in-law broke up with her boyfriend of 16 years because they had planned to move to another state and he actually wanted to follow through with it. He started building a house there in preparation for their retirement. At the last minute, she decided not to move and she broke up with him. A few months later, work became "too much" for her, so she stopped going and decided to retire. She believes she has a physical disability preventing her from working, but she spends her days gardening, crafting, and redecorating her house. She is only 62 years old, and she spent much of her life underemployed or working under-the-table, so she is only receiving $900/month in Social Security. Her mortgage alone is $1,500/month with $7,000/year in property taxes. My husband is sick over this situation and has many sleepless nights. A year has sinced passed, and we assumed she at least had some savings she was living off of, but we found out over the holidays that she only has $7,000 in the bank, no retirement money, and she is only getting $900/month income. We were shocked! She is literally in danger of losing her home within 3 months. My husband and his two brothers recently tried an intervention with her, telling her she needs to go back to work part-time, get a roommate, or sell her house and move into a subsidized Senior apartment. She absolutely refuses to do any of this. Her boyfriend is now with another woman, so no chance of him coming back.

My husband’s brothers believe it is their duty to ensure she doesn’t “lose” the house. Rather than confronting their mother’s mental illness and trying to get her help, they would rather split her bills 3 ways and pretend there is no problem. One of them just lost his job, and the other is fresh out of grad school, unemployed, and a stay-at-home dad living in a small apartment. We are all lower middle-class. My husband and I are currently living with my parents and attempting to save up to buy a house.

My feeling is that paying my mother-in-law’s bills allows her to keep living in a fantasy land. It isn’t a sustainable situation. Are we supposed to pay her bills for the rest of her life so she can live in a 3-bedroom house all by herself making crafts all day? I feel like this is taking away money from us that we could be putting into our own retirement accounts, money for our own (future) children and our own lives. I feel it is selfish. My husband is on board with me, but he is from an Italian family that will (in his words) think he’s a piece of trash if he doesn’t “help her out” which basically means support her.

I don’t know what to do or how to handle this situation. She refuses to seek mental help, thinks nothing is wrong, and says we’re all “ganging up” on her and she worked hard her whole life and now deserves to retire in her home. She is a very nice person, but this situation is making me despise her. She has little equity in her house, only $30,000 or so. She has taken out multiple mortgages over the years. My husband's two brothers live far away, so the brunt of tackling this situation is falling to us.

Advice?