It was actually all of your XH's other horrible traits that you wanted to get away from but the depression is what made you excuse some of behaviors and feel sorry for him.
Mojo, To be clear is this the right interpretation?? I really don't see his "mental issue" problems (depression and/or whatever) as the main problem. I see his selfishness, childlike behavior, inability to be a stable financial figure, cruelness, insensitivity, anger, not being a true father figure to his kids, etc. as his problem. This additional issues of depression or whatever were things you felt badly for and the reason why you excused his p!ss-poor behavior as a father and husband. At least that's how I see it.
While I rarely like the idea of divorce especially when children (whatever age) are involved, I do allow for extenuating circumstances and yours fits for me. I think you went above and beyond in making your marriage last for as long as it did. Your 2bx's behavior after the breakup certainly clinched it for me!!
But what is happiness except the simple harmony between a man and the life he leads? ~Albert Camus