I understand that you are struggling with how to help your child when he is self-destructive and how to get support for yourself as you go through this difficult time. You might consider talking with him about your concerns for his well-being and encouraging him to see a psychologist. If you have tried that already, you may see if there is someone important in his life who could also speak with him about the behavior they see. Regardless of whether he is willing to seek help, you can receive your own support. You may consider speaking with a therapist about your struggle with his behavior and your anxiety.
Because your child is no longer a minor, you cannot force him to go to see a professional. If you feel that he is serious danger to himself, you can bring him to a hospital to have him involuntarily committed as a last resort.