Depression is like a slow poison. I think, you should try all possible things to convince him to have a professional help. Like any other ailment, depression too is, and medication, meditation will only help it go. You can ask your husband to see the doctor for your sake and for the kid's sake. At times, saying emotional things help. I don't know why our society has a sigma when a person goes through a mental turmoil or depression. Like other body parts, Brain too is one, and that too as important and vital as others. So, why make hue and cry if someone goes through the problem concerning mental health? Anyway, go through these articles below, hope you find it helpful. https://www.psychologytoday.com/blog/struck-living/201110/convincing-the-stubborn-accept-mental-health-care http://family.custhelp.com/app/answers/detail/a_id/26513/~/how-to-help-a-depressed-spouse http://www.wsj.com/articles/SB10001424052748703946504575470040863778372
Does he have a close friend that could help you convince him to get professional help? I know it's not ideal but if it's severe, getting help from an expert could be a important. Is your husband religious? If he is, instead of getting counsel from a medical professional, he could talk to a religious leader that he is comfortable with. My friend went through a bout of depression after losing her baby and she sought support and counsel from her church; it helped alot. You can also help by going with him to whatever body of help he seeks eventually. It could be a psychiatrist, it could be a religious leader -- go with him and offer him whatever support you can. Hang in there!
First thing to do is pray for him. Let him know also that you are there for him. Find his close friends who can reach out to him at this time and convince him to seek professional help.