You sound like a wonderful friend. But you have to put up some boundaries for yourself .. As others said you cant make him get help. You need to stay healthy.

What is his living situation? Live on his own? If so he must have a job , right? Is he able to hold down employment?

A lot of Bipolar people are against seeking help due to receiving poor help in the past.

I really hope he reaches out and tries to help himself improve his health and well being .

Best wishes