I am so pleased you have reached out for some support, I am so very sorry that you and your husband are going through such a hard time in your relationship and that he is really struggling which in turn is effecting you, this is so very much to manage along side of running a business, and together too when there is little relief from his emotions and feelings.
The thing is that unfortunately, you can not make anyone do anything. That is really hard to hear but all you can do is support, perhaps provide him with the information, number like Beyond Blue 1300 22 4636 or even Lifeline 13 11 14, and ask him to reach out for some help. You cannot drag him to a doctor and make him get help that he does not want.
What you can do is get some support for you and make sure you are ok during this time, and reaching out here is a great step. You too could call the Beyond Blue line and get some help and chat to some wonderful people who could suggest some things on how to manage this. You could make an appointment for you at your GP if you feel you are not coping well and need some support too. I know this in not very helpful in addressing his issues but you really cannot force any help or assistance on him.
He does sound like he has a lot of childhood issues to work through and this has to be a journey he needs to decide he wants and needs to go on.
I am so sorry that I have not been able to be more helpful today and I hope you can keep reaching out here to come and to chat with us.
Huge hugs to you