Help! Adult Son late 20s has been diagnosed with BPd

[Superdog]

Hello, I am struggling with my adult son who has come to terms with his BPD diagnosis. He has spent the last almost 11 years with frequent outbursts and drug use. Now as he's approaching 30, we found that it is only only getting worse. We go from being the best parents in the entire world and then the next day we are the worst people in the whole world. It seems like the more stressed there is in life like job and romantic relationships, the more he takes it out on us. He realized at one point that we were done with his emotional abuse and then he got a therapist and got a diagnosis. Then he got family counseling to try to make amends to us. Then all of a sudden We became a reason for all the troubles in his life. His therapist met with us and told us about BPD and to follow a script so we won't get entangled and still be able to be compassionate to him. But I'm still struggling with feeling disgusted with his behavior towards us. I'm trying to understand The mental health aspect. I have been dealing with his issues his whole life. Recently he blew up Mother's Day. And then the next day he said he has been using drugs and that's why he was acting the way he was. It was explained to us that this was a classic BPD move. All along he was telling us that he wasn't using. To make matters worse, I deal with chronic health issues and stress is not good for my heart condition.
Can somebody please give me some hope. I do love my son but right now I feel angry and I feel like he's dangerous to my health

Our objective is to better understand the struggles our child faces and to learn the skills to improve our relationship and provide a supportive environment and also improve on our own emotional responses, attitudes and effectiveness as a family leaders