I don't normally post here, but I'll make an exception in this case.
This is the kinda crap (M's unacceptable behavior) that quite simply, should not be tolerated. The only way to deal with one who shun's, is to shun them in return. I don’t buy into the whole, "Oh lets love them through it", thing. She’s an adult who has made her choices. Treat her as one. Sorry, I know that may sound cold, but the only way to fight some fires, is with fire itself.
My JW sister wrote me the "You've displeased Jehovah letter" some twenty-five years ago, about two years after I left the group. (In those days they quickly DF'd you for stating you were leaving. They didn't need any other excuses.) Now granted, my sister and I were never really very close, but I loved very very much my two nephews and niece (the boys were like 8 and 9 and my niece was 5). I decided (at great personal loss to me) to give her what she wanted, and I left her (and her family) alone. Fifteen years later when I had a little girl of my own (and all of her kids grown), she decides she wants to play Auntie to my little girl. Oh, she sent presents and a card that said, "Hug the baby for aunt D". I was appalled at this level of hypocrisy! I threw most of what she sent away, my wife insisted on keeping a few things that she liked. I never acknowledged D.'s gifts and she got the message. When my JW mother wanted to drive up from Florida to visit the newborn baby, my sister happily volunteered to drive her. When my mother told me this, I told her however she got here was her business, but D. would not be allowed in my house. Mom came up by way of Greyhound.
I wouldn’t piss on my sister now if she were on fire. She has made herself dead to me, and dead she will remain. I have no regrets. She wanted to shun me so longs as it fit HER agenda. But when she saw something SHE wanted, it was like all of a sudden the past fifteen years of shunning me and the loss of me being be being able to see and enjoy my nephews and niece grow up meant not a damn thing to her. She wanted to gloss over it like it never happened. Bitch! My daughter is ten now. And while its sad to me that she won't get to know her aunt, it is the best course. One, I don't want my kid influenced by that kinda nut, and two its payback to my sis'. Life is an investment, and this is her reward. Yea, I’m a sonofabitch. It works for me. I treat in kind as I’m treated.
Why did your sister visit? Don't know all the answers. Prolly kinda complicated if I had to guess. Maybe she saw something SHE needed, ya know? Look, there’s a kind of self righteous indignation and martyr syndrome people like this like to play out in their head. They feel in their twisted logic, that their "self sacrifice" earns them points with God. It’s sick, and self-delusional, but this kinda crap has been going on since the beginning of time. The JW experience is just a variation on a theme. So, she eats at your DF’d mom’s house but won’t eat with her? Here’s how she sees it, she’s showing Jehovah that SHE is being loving and encouraging to your mom, just by being there. But eating with her? Oh well, now, that’s just not right. Punish-reward kinda thing. This kind of "treatment" doesn’t acknowledge the anguish it creates for the intended. It’s not love, its animal training.
I’m also sure your sister is feeling lonely and wishes you guys would accept her totally while she is admonishing your mom. Well, this is my advice. Give your sister what she wants. She wants to please Jehovah? Fine. But let her know that it will be expensive. I would let her know, and in no uncertain terms that when SHE changes her attitude toward your mom and asks for your mom’s forgiveness for treating her so badly, then you as a family would embrace her totally again. But, until that time, she would not be invited to any family functions. Period. And if she shows up uninvited, the first order of business is to make amends with mom, or kindly be asked to leave. This way, the shunner learns what it’s like to be shunned. It’s equitable. Doesn’t mean she will accept the terms, but at least this way she knows the rules.
Families want to hold on to what they got, even when it’s dysfunctional. And it’s really hard to cut someone off a loved one who is behaving negatively and destructively. But think a moment about the turmoil and heartache your sister generated with her visit. Was it worth seeing your sister, knowing the misery she caused your mother? It wouldn’t be for me, no matter how much I loved my sibling. You have lost your sister to a mind controlled cultic group where very few once captured can escape. You can’t love her out of it, or scare her out or mistreat or threaten her out. You can only protect the rest of the family from her negative and destructive influence. It’s a choice that you must make. Remember that no choice is still a choice.
I realize this post is not a warm and fuzzy kind of response. I apologize for being so blunt, but this is kinda like someone having to give you bad news. Better to get it out in the open and then discuss options.
Steve