S.,
A friend of mine was in your husband's position. Her back was broken with baby number 2, back surgery, then baby number 3, and in the process of having another back surgery when baby number 4 happened. Unfortuantely, she was the breadwinner, mother of 3 and expecting when things became pretty bad. There was a 4 year decline, increasing dosage of oxycodone, and increased side effects (namely apathy), not to mention the growing money problems. Doctor's didn't want to assume her case, b/c she was so high risk. I don't think her husband noticed the gradual decline being so close to the situation and a stay-at-home dad.
Being on the outside, I noticed these things and became a confidant. We all were concerned about her, the meds, and how this was effecting the fetus and her newborn. Her death (about 6 mo. after baby #4 was born), was ruled suspicious, but there is no doubt in my mind that she overdosed and mixed in alcohol and tobacco, and I'm certain she sucided. I know this isn't what you want to hear especially with a loved one on the same road.
The best advice I can give you is to stay proactive about this, get involved with the doctors, his work (co-workers and boss), and if you gave to be a parent to him, especially if the meds are affecting his mind. Make sure you have authority for the doctors and psychologists to release medical information to you. (The mental health is usually a seperate form) This way, you both can freely communicate about his condition. Get control of the money, for the sake of you and the boys. (I know this will be a blow to him, yet we are talking about an extra ordinary case). Make sure wills and life insurances and living wills are all in place (His road will either lead one of 2 ways, life or death, be prepared for both). You never know if he will be driving and an accident happens. Who says you every are really prepared. When you have things in order, you're going to need to talk with the boys. I know you want to shelter them from this, but they will be seeing the effects and watching both of you closely. You will need to be honest and open about their father's condition. I'm not suggesting every single detail especially if they are little. Hopefully, dad will be on board for wanting to get well.
Do not scare him into divorce. That is unless you are ready to persue it. What ever you do, set your priorities. Give him to choice. Either he wants to get well or not. The entire family has got to be on board with this as well, his family, your family. You will need a support group, a group removed from the situation, but also who has been through something like this. Get your support in place first!!!! Get educated and informed!!! Get the gameplan!!! All this before bringing in the friends, work, family. Give the choice to him, then bring in the family.
This is going to be really hard for all of you. I helped my friend to the best of my abilities, even showing tough love. She was unwilling to get well. Both her and her husband would rather whine and sweep this all under the rug. Her work was the same way, assuming that she was smart enough to take care of things the right way, even in her depraived, and post-pardum state. What an very wrong assumption.
ps. I'm re-reading this post and want to mention something about his work. They, will no doubt want to be loyal to him. If you do decide to contact his boss, it could lead to his dismissal. However, I remember an Oprah episode of a wife in an abusive situation who documented with dates and specific events that lead to the imprisionment of her abuser. If his situation turns nasty (heaven forbid a divorce and custody), you will need this sort of information to protect him and yourselves. (I'm not suggesting that he will become an abusive husband here.) This may also be grounds for checking him into special programs to facilitate his healing. If legal counsel becomes involved, this is the sort of information they will need. Not to mention the doctors.
My prayers are with you and your family.