Oh dear!
I know too well what you are going through...
Melt downs are regular unwelcomed guests in our home too.
Last summer it was not only a melt-down.
he went wild, distroyed the kitchen, in the children's presence.
I don't know if knowing you are not alone there, comforts you a bit, or if a virtual hug does, but if so, I send you a big and warm hug!!
What i'll write now, might seem hursh, but it's not meant so.
We must set our priorities.
First priority to me ( i'm sure to you as well) are the children.
If my dear husband, whome I love with all my soul, would have refused to go to therapy ( daily visits to a psychiatric day center), I would have to ask him to leave home.
Exposing my children to a father that damdges them, was something I just could'nt take any longer.
I think he might have realized it, without me having to say it.
Thanks to the help he and we are still getting, this summer is ok.
I understand your husband is afraid of doctors because of bad expirience.
Maybe you could look for recommendations from people he trusts, and call only a recommended doctor or unit?
In any case, it will not help him, if he will take you and the kids down with him.
If he refuses any help, I believe you need to focus on saving the kids and yourself (and I know how hard it is, on a time like this, to focus on anything...)
take care
big hug
shlomit