Hi Alex1968- sorry you're going through this. A lot of spouses/friends/relatives just don't understand. There is a wonderful group out there specifically for these people. I tried to post a link, but I'm too new for the system to allow me to do so.
Anyway, the group is NAMI - National Alliance on Mental Illness. The website is the name (nami) dot org. Tons of good material there, it's specifically geared towards friends and family members to help them gain some insight. If he won't go to the site himself, find some relevant material, print it out and leave it laying around for him to look over or not.

Another suggestion is to see if there is a DBSA (Depression Bipolar Support Alliance) group that is meeting in your area. Lots of support there and people who truly understand. There may be other advice that people will have for how to approach your spouse.

Best wishes to you during this difficult time.