Jeri Ann,
I'm so sorry to read about your sister's reaction , as a grandmother her actions are questionable . I have a similar situation with my ex-wife and my grandsons , it hasn't reached the point you described and I hope it doesn't . The question is who is trying to protect who and from what ?
Your sister may appear toxic to you as I feel my ex wife was to me but when she was alone she felt bad about her actions , she knew her behaviour was wrong , all you can do is give them time . This is true of my sister , I never thought she would accept me but she has through my mother's help but it has taken time . I try not to write people off too soon and it's gradually paying off .
As far as this thread is concerned we must also consider it's not always about us , I know we can and do touch a nerve in others , harsh words or criticism aren't aimed at us as much as they are being used as a smoke screen . Often it's a case when we reveal our trans situation others find the opportunity to open up about their own issues , it's happened on numerous occasions with me .
They don't have a problem with you , they have a problem with themselves , other people also live in the closet over personal problems .