I felt the same exact way before I left my ex-fiancee. Granted we had only been together 3 years and didn't have the child addition to our equation but I had those same feelings. It was like when he was gone I only thought about the good times and how much i wanted to work things out but then as soon as he would walk through the door my mood would change and I just wouldnt want to deal with it.

For me the decision was a lot easier because we were renting and didn't have any children and never went through with the marriage so we just lost the money we had put into the wedding (which wasn't a lot at the time) and we had to decide who took what. Although, we did have 3 cats that are basically my children and he felt the same way so that was pretty hard.

And going through 2 divorces (my dad and my mom then my dad and my step-mom) I can tell you that, although Im pretty screwed up, I would have been even more screwed up if they would have stayed together. Im still not sure how to show affection to others bc thats not how I learned. I learned that screaming and hating each other were the norm. And I think if they had stayed together that would just be even more reinforced in me. And kids aren't stupid. They know whether you love each other or not whether you hide the fighting successfully or do it in the living room. So staying together for the kids kind of hurts them on multiple levels. But you also mentioned the mortgage and many other factors like loneliness that make the decision harder.

I think deep down you know what you want/should do. Im not going to sit here and flat out say "stay together" or "get divorced" bc I dont know either of you or your relationship but I bet that you know what you need to do for yourself. It just takes some time to come to grips with the decision your heart has made. You both will be in my thoughts!