We were together for almost 20 years, married for 14. He checked out of our marriage and parenting, became a kind of bystander in our lives, about four years before I decided I wanted to separate. I thought it was my fault because I'd had problems with depression and anxiety, and actually, looking back, he made me believe it was. I tried and tried to make things work, for the kids, but ultimately it was never going to work, because he didn't want it to. He was just to much of a coward to say it. He didn't want the responsibility of being a parent, or of being married with a home to run, he was immature and selfish, but he made me believe it was because of my mental health problems.
I'm not sure he has any redeeming features - I only put up with it for so long for the kids. We separated almost 18 months ago, and he hasn't paid a single penny in child maintenance for his two children, and only has them one or two nights per week. His true colours sure have come out! I'm sure it'll bite him on the arse at some point though 
I found out after we separated that he'd had an affair with someone he worked with, about four years earlier, at about the time he checked out of our marriage. Funnily enough, I've not had any bouts of depression or anxiety since we separated...maybe he was the cause of those, because of how he treated me!
I'm much happier now, and so are the kids!