Unfortunately, after being diagnosed with BP things don't magically get better. They often get worse, and there is often a long period before medications can be optimised, there are horrible side effects to deal with, the debilitating depressions which have already been mentioned.
What hit me the most was that I could no longer trust my own brain, which had previously been my greatest asset. I could not trust myself to be able to think clearly and to produce the quantity and quality of work that I expected of myself and that was expected of me.
I have never had great self esteem, but following my depression, diagnosis and the following years of medication trials (some people are more difficult to treat than others!), any shread of self esteem was completely gone. I could not imagine ever being good enough to be employed in any way.
This is a common experience amoung people with BP, where they underestimate their abilities and end up underemployed even when in remission... part of this is due to the concern of our ability to function when the next episode comes along.
I hope this helps you to understand what may be happening to your husband. I also want to commend you for your willingness to help your husband. I hope that you are able to find some way through this difficult situation.
I agree with the suggestion that communication is essential. My husband has supported me through this time, he is an amazing person and I often don't know how or why he did it. One thing that really helped, was his encouragement to take little steps. In my worst times, he would often call me to wake me up (he left early in the morning), then call me again to help me get through the difficulty of getting up and dressed and out of the house. (I know it sounds really stupid, but there were many days that I just couldn't get out of bed, or leave the room, or leave the house - when you think of what you do in a normal morning, get up, have a shower, find clothers, get dressed, breakfast, clean up kitchen, feed dog etc... it becomes overwhelming and completely impossible, the littlest things become inhibitry and my only response was to run back to my room and hide - and I mean really little things, like the clothes being downstairs in the laundry, or not having a towel in the bathroom!)
I guess I am going into such detail coz I want you to understand how broken my brain was. I don't know what your husband feels, but maybe it is something like this.

For the immediate future, I would suggest you support and encourage his treatment, both complience with medication and any therapy he is recieving. Also try to encourage him to move forward with baby steps. Both your expectations and his expectations need to be appropriate for the situation he now faces. Some days, getting out of bed is an achievement, others, going outside or doing housework. As things get better then a flexable or part time job would definitly help both his recovery and your finacial situation. You may also be able to get some assistance.
I am sorry if this is not what you wanted to hear. It is a long and hard journey and I wish you all the best with it.