[TOS'd]

I've dealt with/dealing with a similar situation as well. Best thing to happen was gf just straight up blocking her mom. Gf does have a sister who still lives with the mom, although the relationship between siblings isn't the greatest (sister is basically becoming a mirror of her mom), but at least we would know if any of these empty threats were indeed real. The only times the mom ever reaches out is to ask/demand money. Saying shes she needs money to pay the bills, yet she is going on all these cruises and trips with her friends. Always saying things like her kids were a burden and if she didn't have them she would have a much better life. So because she had them, they now "owe" her. I think the last time the mom was unblocked, I answered the phone and told her any communication with her daughter would be through me. All she did was yell about how she can't speak to her daughter and that she needs money for bills or else she has to sell the house and then become homeless.

Other forms of helpful things for her were therapy and support groups for daughters of narcissistic moms.