Wow! That is a lot to deal with at once. I think that for some outgoing kids, being away from the social whirl of a brick and mortar school can be very lonely. You mentioned the one friend and the likely bad influence -- would it be possible to dilute her influence by expanding physical contact with her peers (not necessary age peers) if medical limitations will allow? Considering how far advance your DD11 is, could you get medical authorization to remove all the pressures of academics for a month or so? It seem that you have valid reasons and her mental health and emotional well-being are so much more important.

I hope it gets better with the approach of spring.