I also find myself in a similar position, sort of. My AH and I are not separated and I am not ready to make a decision about the marriage. At this point I've made it clear that I'm not happy with the way things are and cannot continue. He has not quit drinking. He still believes he can cut back. I see no change, and without some kind of active recovery, I can't commit to the marriage.
Anyway, we rent our house and just found out that our landlord intends to sell it. We *could* theoretically afford to buy the house, but if we did and ended up divorced, I could not afford it on my salary. I also couldn't afford to buy him out. I've said that I don't want to buy the house due to instability (he's considering a job in California, I have said I won't move the kids because they've changed schools twice in 3 years and have only just settled where they are).
He isn't listening to my perspective on this.
I really relate to your issue with the kids - I also would be gone from this relationship if they weren't part of the picture. It's challenging to try to figure out the next best step, when you're working to keep them safe and happy. It's also difficult (for me) to consider the best options when I'm not quite ready to put an end to the marriage.
I don't have any advice, just wanted to say good luck with your decision.