As as a mental health patient with a mood disorder that has been called bipolar II to mood disorder not otherwise specified, I feel it is the patients responsibility to comply with treatment. I always did although I have never been violent. The result of compliance is often a life that is good, that is like people who dont have a mood Disorder. It in my opinion is up to your son to make his life good. If he won't comply with treatment, his life will not change and your help won't help. Drugs AND alcohol are very bad for a mood disorder or any mental illness.
Weed is horrible...it often triggers worse disorders such as schizophrenia.
Maybe if you don't try to save your son from his mood disorder, he will begin at to comply with treatment from a psychiatrist. You are really doing a good job as Mom. I really admire your growth and strength. Take a minute to pat yourself on the back. This is hard.