You are so good to be so supportive. It is really wonderful that your husband sees that he is having trouble as well. There is hope. There really is. The feelings he is having in regards to work, friends, and life in general are very common in those who are depressed. There are many avenues for help. If you do not have insurance that will cover care you could try a few things first. These have been clinically proven to help with depression. These are great avenues to try first UNLESS YOUR HUSBAND IS AT RISK TO HIMSELF OR TO OTHERS. If he is suicidal or at risk of harming others I believe you can go to the Emergency Room and they can direct you to help.
1. Excerise - this stimulates the a part of the brain that is connected with emotions, etc. Make sure he gets his heart rate up for a good length of time.
2. Cognitive Therapy - "thinking" therapy, you can actually do physical therapy for your brain and can truly REWIRE your brain and make PHYSICAL changes to the neural pathways by working on changing the way you think. It is amazing. A good book for this is: "Feeling Good: The New Mood Therapy" and its accompanying workbook "The Feeling Good Handbook" by David D. Burns MD.
PBS just aired a special last night called "Depression: Out of the Shadows". It was really good in relation to showing how clearly clinical depression is a MEDICAL disease that is for the most part treatable.
It is important that you continue to support your hubby as you have been doing. You may have to let things he does or says (as long as they are not physically abusive) roll off your back. Just remember that he is suffering in a black hole and may not see the light. I know that it is really hard for you too. I can tell that you are a wonderful wife and just right for him.
The advantage you have, in being healthy, is that you still have your wits about you and can see who your husband really is, the promise your lives hold, and that all is not lost. You can see "the light".
The most important thing you can do, in addition to the above, is pray. The power of prayer can be felt no matter where the recipient of the blessings is. I know this to be true. The Lord can help even when we feel that there is nothing we can do. He knows all that we go through and He knows just what we need. I believe in the power of prayer.
Also, you can help make sure that he has something to look forward to everyday, even something small. (A favorite meal, time with you and the children, a chapter in a good book.) Also, if he can have something major to look forward to every few months like a weekend trip or a concert or symphony or a visit from family and friends that will help.
All of the above things being done, medication and therapy may be required to pull him out of this. Try to help him see that those things are okay and that he is not somehow weak for taking that route. If he broke his leg he would not refrain from going to the hospital to have it set, or if he had cancer he would not refuse care, or if he had diabetes he wouldn't stop taking his insulin. To not seek care for those things wouldn't be considered strong, it would be considered unwise.
It is exactly the same with clinical depression.
I hope these things help. Keep praying and everything will work out. You can get through this.