I'm sorry that you are dealing with this.
You have mental health issues in your life that need your care and concern. That must be your priority. It sounds to me like your relationship with this guy is toxic. He is continuing to use drugs, even though he's told you he would stop, and he's blaming you for it. That's not a healthy place to be. I hope that he makes a decision to be sober and, in the meantime, you can do what you need to do for yourself.