TheVanguardSix This all sounds very difficult.
Are you from a culture where parents live with their adult children?
Can I make a few suggestions.
Draw up some guidelines of what you and your dh would be willing to allow, and then tell your mother and stick to it. Whatever it is.
You can be honest and tell your mum her visits have put a strain on your marriage and it may fail if she continues.
Her behaviour is not normal and by allowing it for so long you have all allowed her to think it is normal. It is not normal or healthy.
Can you afford to visit her (alone no kids) for a weekend or few days and tell her all this on her home turf?
Re "he difficulty is, my eldest brother wants her to rent out her house, live with us and give us rent. I want sanity, not money."
Please tell your brother his is not ever going to happen. There are many choice.
She can sell and move to a different property, she can sell and move to a home, or other relatives could offer to house her, you will not. No discussion, you will not have her to live with you, rent or no rent. End of.
You do not want to handle an inheritance from her, you say, be careful you do not lose out as it sounds like you have supported her for years!
"Dad's been gone 14 years and the house has just rotted."
My mum lived in her house for 5 years after dad died. We (sis and I) thought it was because she was so attached to the house. It was not. It was the overwhelming feeling of fear at having to sell it and do it all. Si and I offered to clean house, arrange estate agent viewings and pick estate agent, mum agreed, sold, moved into retirements flats and all was well.
"And I think over the years, observing how she's handled her own life has made the prospect of her living with us just totally unattractive. We've suggested independent living. No way. She wants to live with her kids. But she doesn't want to live with her kids." What does this mean?
If she wants to live with her kids, well she cannot, it is not a given and in Britain most families are not three generational homes. Just be clear, no, sorry if you want to say sorry, but I cannot handle this.
"I don't know what she wants." well you are going to have to leave her to it. I know it is hard, but really your marriage is at stake!
"...she speaks in tongues the moment you discuss real life with her." Is she religious, can you get her pastor or priest on side. Or do you mean she speaks her native tongue?
"I've learned to suggest very little to my brothers. Weak, I know. But radio silence is their normal response." Call a family meeting and tell your brothers you have had the bulk of looking after mum for most of a decade, their turn now. Be clear and firm.They can help or walk away, but you are not taking responsibility any longer.
You may need assertiveness training to be able to do this. I would really look into this as she has been walking all over you for years.
" So naturally, I feel like a beast." So begin with positive self talk.
Your mum has convinced everyone is very nice, but you know she is toxic to you at times.
So say t yourself " I am going to make moved to sort this all out so I can be free to live my life with my lovely dh."