I know as the wife and mother in my home, if I'm not happy - no one else will be truly happy. I have learned to put an end to my suffereing from depression long before I got married and part of that was to remove my mask of happiness, deal with my angst, hurt and pain.
Children aren't as naive as you think they are. They can feel when something just isn't right.
Get to some counseling. It will truly help but it may take some tries to find the right counselor for you but it is well worth it if you are willing to do the work.
Depression can stem from anger but mostly from my personal experience it was just a deeper level of hurt and pain and replaying the hurt and pain in every thought and actions that kept the cycle going.
Sounds to me like you are allowing your thoughts to be concrete like how you think a thing is the only truth when in actuality it is only ONE truth. Great counseling helps you to see more than one solution and more than the doomed thoughts you've been nurturing.
One of the greatest movie lines in history was Cher's line from Moonstruck when she slapped the male lead and told him to, "Snap out of it!":
It will take counseling to help you snap out of it. In the mean time your family and you are going down in a sinking ship. Don't let that happen. Love them and yourself enough to get good counseling and to actually do the hard work to get well and have richer and better relationshiips even if it means the end of a marriage or the end of this marriage as it currently stands.