Got an Answer?
It sounds like she is really struggling so my suggestion is one of those little guardian angels or a dragon or a crystal that is symbolic of strength or love or protection. Include a Christmas card where you have written exactly why she is so special and strong so she can read it when she is struggling and know that you think she is amazing.
Insist she leave early as she has another important event to attend ( dinner at your place)
The best thing for her is to minimize time spent with them. She probably won’t cut them out straight away but the more she reduces the time and spends it with normal people then she will see clearly.
Buy her a fake cast so she can take a photo of herself to send them and say she can't make it she has broken her leg and nobody can visit because the doctor is worried she has some weird contagious bone breaking disease. Kids and husband are also house bound. I may or may not have been dreaming up some excuses for myself.