Yes, the kids have to come first.
I would highly recommend that you talk to some folks in your shoes. Check out the forum link above and maybe attend an Al Anon meeting and see what they have to offer. I would also say to tread carefully and put a lot of thought into how you want to handle this. If he's in denial, there may be the risk of alienating him if you try an intervention type conversation. I would imagine that getting some input from others who've had to deal with a similar situation would help you figure out how to approach it.
Good luck to you and your family.