As a Vice President of Human Resources, I usually don't recommend this....however if his boss was disclosing his medical information, it is not only a violation of American with Disabilities but also of HIPPA (which is huge right now). You seriously have an option to sue him for disclosure - and I bet you could find plenty of attorneys that would love to take the case, and ADA may even provide you with one? I suspect his company would settle first (and probably term the boss - which is what he deserves for being so stupid and assanine). One way to pay for the loss of income.
However, keep in mind that if your husband is a mess - he could have also been doing a poor job at work and was termed for performance (would you really know)?? But again, that would be irrelevant to the medical disclosure situation - and actually the threats, therapist etc would help in the case to show that he was distraught over all of this.
If it were me - I would pursue this and if you win - I'd put that money somewhere safe - if you decide enough is enough - YOU may need it. One of you has to be thinking clearly and rationally.
And honestly, you are a saint to deal with this. I also believed that marriage was for better or worse - but let's face it honey - he broke that contract when he decided to have an affair! And is this a marriage anymore or a babysitting service?
Just my two cents

Course this is coming from a divorced woman so what do I know about marriage - lol
P.S. let me know if you need assistance with legal research - I have some great websites on employment law.
Cherish