Welcome to the forum wonder woman.
I'm sorry to hear your family has gone dog on you after all this time.
I'm in a slightly different position as I didn't get baptised, so I'm not shunned, but do have a disfunctional relationship with my family.
When I finally realised it was't The Truth and they got snarkey about it when asked difficult questions, I cut a deal with them that if they didn't talk religion, I wouldn't make them defend their church leaders. They don't often break the agreement, but when they do I don't stand for any nonsense.
I made it clear to them (and had to repeat that just a couple of weeks ago) that I didn't choose to be born to members of their church, that they made that choice. They chose to raise me in a church that treats it's non-believing children badly, not me. They chose to raise me in a church that had a history of failed prophesy, something that was warned against in their own Bible. They chose to sweep that information under the rug to hide it from me. Then they lost their moral high ground by being dishonest with me to protect their church leaders (I had asked them questions and received answers that were blatantly and provably deceptive and lies), so now, if they want their moral high ground back, they were going to have to answer my questions with honesty and integrity, without attacking my character or using any of the many tactics they have criticised other religions of.
If your mother tries to tell you something that you know isn't right, insist that she shows you the proof of it. E.g. If you are not DF/DA and she says she is supposed to shun you, insist that she sends you an article that proves it. Also, let her know in no uncertain terms that if her, or her family, do anything that results in you being DF/DA, that that is their choice, not yours, and any bad behaviour towards you is a result of their choices, not yours. You just want a family. Now behave yourselves and act like one.
The hard part is to get that message across nicely. That's a skill I don't have :-)
Never discuss Bible. It never has a happy ending for either party and JWs don't believe it anyway.
Chris