It is possible to help someone who is also trying to help themselves, but this doesn't seem to be the case. It sounds like the only one worried about his using and committing crimes is you. This is now causing you to lose sleep.
I say this as gently as possible....Step away from the addict. You cannot help him. If and when he wants to clean up his act, he will. If you continue to communicate with him, all it will do is keep you upset. If after six years your support hasn't caused him to change, it isn't likely to happen.
I know it sucks, but there isn't anything you can do for him. Please take care of yourself.