I know your situation is not a positive one, but when I read your post I get a very positive feeling that your future holds what you are looking for. It sounds like you are doing the right thing. And I get the feeling you have two great kids who are lucky to have a father like yourself.
I take it your wife has depression, and you sound depressed as well - and rightly so. Your situation is a good example of needing to move on because in the end your wife can only help herself. I think she will be better off in a different situation. Maybe she will be forced to get out and get a job and become more social like yourself instead of being so passive in life and then maybe she will regain control over herself.
Sometimes it's simply a choice of one person suffering or five people suffering, and you just need to do the math and make the necessary move before the years go by and the regrets of "shoulda coulda"'s eat away at your soul...