No, you didn't make him that unhappy. Trust me, if he had been so unhappy, he would have left a long, long time ago. Depression makes people think and do things that they normally wouldn't have done. They look at life thru very dark and dingy classes, whereby, we are looking thru clear ones.
Yes, it can be difficult dealing w/the exact opposite image of the man you knew, but you have to stop trying to see him as he once was. You need to find a way to at least accept him for who he is now...a stranger and no expectations. Can you treat him like you would the mailman for now? He's going to be a mixed up mess for quite some time.
I would like for you to take some time and read up on MLC (again). The things you mention are all typical of MLC/depression. It would help you better understand what is going on and hopefully help you to turn the focus back on to you since this is a long process.
I would like to hear more about you, what are your dreams for life about, how are the children, what are their hobbies, etc. It's time to start really living your life for you and your children and leave that man twirling in the wind.
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.
