Seriously, there’s the tribe you were given, and the tribe you make. Don’t waste your time with people who are petty - life’s too short! If you want your family to be otherwise, lead by example. But don’t do so with the hope of changing hearts or minds, you gotta do so because you believe it has value for you and only you! Good Luck!
The thing nobody ever explains is how do you cut off toxic relatives without cutting off the ones who have fallen prey to the toxins (like the OP’s mother)? How do you deal with the ones whom you love who aren’t exactly toxic, just hard work? I’m not going to cut my mother off because she’s cranky and negative about other people, but I don’t enjoy those aspects, either.
You have to make evaluations on an individual basis, I think. If Mom’s annoying or bothersome that’s one thing. If your every encounter with her becomes a vortex of negativity and sends you spiralling, then you need to reevaluate. I’m a very big believer in highly valuing and ruthlessly defending my own mental health. Seen too many people sacrifice theirs to some imaginary propriety/ obligation!