To MsMS315. I again read your post and can see that your husband has been highly resistant to taking positive steps.

Could your family members, especially those who have suffered from the suicides in his family, somehow come forward and confront him with you and initiate a forceful motion to get help at a psych facility? An intervention like confrontation?

I know this site prohibits you from talking of actual current self harm threats. I will address it because it's frequent with depression. If he ever does talk about suicide, you can take action. If he verbalizes it, you can go to a county psych facility and have an order drawn up that will be acted upon by police. The police would come and escort him to the facility. Or you could just call the police and they will do the same if time does not allow the trip to the psych facility. He would be transported in an ambulance.

Another post described depression this way:

Depression is like cancer
Some are curable
Some are treatable
Some are terminal.

Supportive, professional ,caring action can prevent it from being terminal.