It sounds like you are going through a lot, and by the sounds of it, you are feeling down about your luck. I go through periods where I feel exactly like this, and I feel as though nothing I do is right. Sometimes finding someone to have a yarn to is what gets you through moments like this.
My advice would be to talk to your wife, you said she is bloody amazing, I'm sure she loves you with all her heart, as your kids probably do too. You are not alone in this battle, and you are loved I'm sure.
Maybe having a yarn to your wife or a friend about things, or even going to see your GP, just to talk about how you have been feeling.