I'm bipolar 2 as well. It destroyed my marraige and plunged my ex wife into a cycle of depression. Now I don't want this to sound like I blame her for what eventually happened because I don't, even a little bit. What she needed to do was either force me to get help and take my meds, or throw me out.
She couldn't bring herself to confront me, and it just went on and on, I got abusive mentally, lied, drank,spent money indiscriminately, forgot to go to work and just rode around all day or sat in the library and just generally became a huge pain in the a**e. It eventually got to the point where I became impossible to live with and we were divorced. That was the best thing for her and the kids by then. I wish I'd got a handle on it and dealt with it earlier.
As for the therapy, don't hold your breath. If it's the GP that has told him he doesnt need meds,ignore that, GPs are generally fairly clueless about mental health.
When he has a rage,contact the local community mental health team, usually available through A&E at hospitals, they will connect you to the duty psychiatrist, and usually arrange to see him really very quickly(usually within hours) and provide diagnosis and support through the team.
But, you really need to think about pushing him gently towards psychiatric and/or drug treatment rather than waiting for almost any kind of talking therapy, which doesn't have a huge success rate for bipolar anyway.
Hope that helps