Michele, Do not diagnose your h's situation for him. He most likely will not believe you when you tell him that he's in mlc. Depression is something he can relate to, but not a crisis. They need to figure these things out for themselves. Suggest gently that he see a physician. Now that you've made the suggestions, drop it for a while. He's got to make the decision to go.
I wouldn't raise any more relationship issues at this time. As you are aware, depression is one of the driving forces behind mlc, right along with unfinished childhood issues. Just leave him be to work things out for now. He needs plenty of space and time, no pressure, no expectations from you. If you wants to talk to you about how he's feeling, by all means listen and validate, but do not offer up a lot of opinions. He is looking for a friend and a sounding board...not a mother.
It's time for you to start taking care of yourself. Start putting some money aside for those days when you may need it. Also, you need to begin preparing yourself, that if this is mlc, he may very well begin to self medicate by spending tons of money and not paying the bills. Take your name off of any credit cards that you can, set up a separate checking/savings again, just in case. BTW, do not even think that your h will not do such things....they all do it to some degree, some just a little bit, others a lot. They all tend to follow the same script with comments, sentences and behavior. The acting out is something that is as individual as the person going through it.
So, step back, buckle up and prepare yourself for a very long ride. Please do not take anything he says or does personally, for it is the depression talking.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.