How to set limits with RAD "adult" and holidays

I need some advice (or sanity check) on how to set boundaries this holiday season. My RAD dd turned 18 a few months ago and "ran away" about a week after. Adopted her at 7 and have a non-RAD younger school age son. The decade she lived with us was a near constant battle. The last 2 years involved psychiatric hospitalizations for a psychosis then mild homicidal ideation (with us as her target). Our child had us living in constant drama and in the last 2 years, fear. She has told her most recent therapist how much she enjoys seeing us upset and we have found journal entries where she is making plans to ruin our lives. She shows no remorse. The tricky part is she is adorable, charming, and skilled at eliciting the goodwill of others. She will torment us then as soon as a someone else is around, turn on the charm and complain how mean we are. She has asked to come home and we have said no as it's apparent it was no longer healthy for any of us. Now she visits and is more pleasant unless we say something she doesnt want to hear. She is living with a relative (until she enters a job training pr) who think she is wonderful and gets mad if we say anything otherwise. This relative works for the same company (diff office)and is suggesting her as a babysitter to coworkers etc. As the holidays approach we are getting pressure from others to make sure our dd is included in events so she doesn't feel left out. When we are around her we are anxious. At the same time we are trying to set boundaries around our own health and well being. It makes us look like jerks. How do we maintain our boundaries and sanity? How much do we try to explain to our loved ones our fears or do we just let it go and suck it up because they won't get it?