So I have become really good at not giving SD20 supply, to the point that she was stressed out and started doing anything to get an emotional reaction out of me. To be clear, I did not give her any negative attention either.

SD20 seemed outright miserable and very desperate since she could not get narc supply from me as she used to (obviously in hindsight). 

I was polite, but have been working on my computer, so anytime she would try to get my attension, I would say, "oh, I am sorry  I am swamped I have an important deadline." and if she kept pushing I would say, "I am sure you can find a way to solve it".  Thus, whatever she was trying to get me to give her compassion about, or take on the responsibility to fix, I would send the responsibility right back to her. She clearly, did not like that she could not get me to play the rescuer any more (drama triangle). At one point, she was standing next to me and making noises of despair, just to get me to react, I had headphones on, so I just ignored it, pretending to be listening to music and typing like crazy on my work thing. 

Then she talked loudly about how washing one's hands to avoid corona is just stupid. Knowing that the old me would react, but nope no reaction. I am working. 

Then she stole a beautiful gift from DH to me that stood in the living room and placed it in her room. That did get to me, and I was hurt seeing how it is of high sentimental value for me. I did not want to engage in drama, so I texted DH and told him. He did get the thing and told her calmly not to take something that was not hers. Then SD lost it started screaming, slamming doors, drawers, etc. She even went into the room I was sitting and hit a button as hard as she could in front of me and she was trying to watch if I reacted. I was listening to music and typing, so no reaction. 

Having healthy boundaries is an on-going battle for me, and I have been working through emotions of guilt for SD feeling unhappy in our home. However, truthfully she has a pretty sweet deal, rent-free, and no chores. Her only responsibility is to finish HS.  

After her anger outburst, she moved out and went to live for free at her caring friend's apartment (the one she calls the free taxi driver). They have been drinking and having a really lovely time. Any time DH called, SD was delighted, her friend is very much a kind caring problem-solver person, thus a fruitful source for narc supply.

Now, what really hurt me is that she called a family member of DH. A person I care for deeply, he is the only one in our extended family that is very similar to me (or how I used to be), a caring problem-solver, that works hard to have a peaceful, happy family. Of course, if someone in the family should take my place as the rescuer, it would be him. So he called DH, and was all worried about SD20 (while she was happily partying with her friends), he kept on asking if SD is not happy in our home? DH did not bite. DH just said, she complains a lot all the time,  I have told her my opinion and if she chooses to be miserable, that is on her. The family member got very aggravated like we were not taking SD wellbeing in our home seriously, and that we should work more and make changes to ensure her happiness. DH did not let this conversation impact him, so he is enforcing healthy boundaries on this one. 

Honestly, I was both hurt and triggered by the family member. Emotionally I felt very guilty for SD feeling unhappy in our home. I have for years worked so hard for her to have a happy childhood in our house, but she was too damaged. It got me nowhere. So when she could not get supply from me, she discarded me, and then she tried to triangulate this family member to try to take away my happiness. Soon she will be back to try to get me to give her supply again for sure, but I have changed, so I am dedicated not to be a source of supply. 

I guess setting healthy boundaries will make her unhappy, and other people will not be pleased, but for me, taking my power and happiness back is the only right thing to do.