There are these times in life, when we are completely broken and without any hope for our future, when all we had built collapses, and we do not know who we are anymore.
You are not crazy, but you are for now broken.
And the chronic unrelenting stress in the last two years could definitely trigger medical depression--it has to do with skyrocketing cortisol that never gets a chance to return to normal because the stress is so constant--and I agree that you should speak with a physician. It is not possible to think away medical depression and walks in the park or being nice to oneself--as so many might suggest when you are in pain--will not work.
I believe you when you say he is your soul mate.
What I find is most hard for many of us is the ability to take the long view. To accept that some stories take YEARS to unfold, with many chapters. Like a long Russian novel. Some of our stories are like that. It is not over and done in a year or two or even five. Some stories between two individuals are very very long.
Life has broken you so that you can rebuild yourself in a new way. It is true. You will stay underground for a time--as heroines in myths who are lost in the wilderness or who descend into Hell--and then you will claw your way back up. This will be your story over the coming months. It is a story of transformation through pain.
Let your children know that you are broken right now but not forever and that you love them enough to seek help for yourself. They are terrified.
Release your man to God and accept that God has separated you from him for divine reasons you cannot know and that the future between you and the man you love is completely dependent on God's will.
Hold on until hope comes back. Get help and hold on. Your story is not over. But to get to the promises of tomorrow (and they are there--the cycle of life tells us this) you will have to hold on right now.