Oh My!! I have been in your shoes... my oldest son was the addict in my life. He was ALWAYS threatening suicide. I called the police, hauled him to rehab, got him into sober living (which he was eventually kicked out for doing drugs). Nothing could have saved my son, the mental illness and addiction had literally sucked the life right out of him. He did commit suicide last August and I truly regret not telling him I loved him (despite his choices) the last time we spoke on the phone. The best advice I can give you is to truly commit to taking care of yourself. Do let 'him know that you care about him, love him, etc and will be there for him when he is TRULY ready to get help. That is what we did but the call out for help never came. I understand the anger all too much, to this day I am still angry at my son. I know it will pass in time but... taking care of you is the most important thing you can do.
Hugs to you,
Jalapeno