Sounds like he is depressed. I know we are not supposed to "take care" of them and their stuff, but if your child, or good friend was depressed, would it not be appropriate to say, "hey, I care about you and seems like you have been depressed lately. What are you going to do about it?"
My AH is extremely depressed, and maybe even bipolar. Has a couple really bad bad episodes a year, but won't seek help for it. Then he turns to the bottle, then the vicous cycle starts all over again. Depression, bottle, honeymoon, depression, bottle, honeymoon, depression, bottle, honeymoon. Yes, it is sad and all I can say is you need to do what is best for you and the children. Can you live with it the way it is right now, with no expectations of him getting better? I too am in the research business and want to weigh all the pros and cons, and not let emotions take over. But, sometimes our emotions are what motivate us to make changes in our lives.
I too have struggled with ending a 16 year marriage, with a 6 and 8 year old. But, it isn't a true marriage. He has accused me of not honoring our marriage vows, for better or worse. But he didn't honor our marriage vows, as he abandoned me and the children for the bottle. I like to think of it as adultry. He has a love affair with a bottle.
Peace! Take care. And don't forget, you can take baby steps. You don't have to make a bunch of changes all at once. Start with things, like getting finances in order, getting house in order, making lists, etc. Once you start making some small changes, the BIG changes may not seem as big.