I think the most important thing that has to happen is that your husband has to take steps to improve his mental state. If he's not seeking treatment, nothing is going to improve.

No matter what you're feeling through this, don't ever think you're stupid for feeling that way. You're having those feelings for a reason. It does hurt and it's good to recognize the feelings you're having. Try to understand though, he may not be thinking clearly and is likely acting on thoughts he's having due to the way he's feeling because of being depressed. In a clearer, more rational state of mind, his thoughts will probably be much different.

If you are supportive and encouraging, it could make all the difference in your husband becoming healthy and the two of you staying together. It also will be helpful to learn as much as you can about depression and how to treat it. When my marriage was falling apart, I didn't know anything about depression and everything felt so hopeless that I didn't even try to stop it from happening. If I knew about depression I'm sure I wouldn't be in the position I'm in now.

If you love each other and are willing to work for it, I'm sure you can save your relationship and it's worth the effort!