you're smart, you just need to listen to yourself more.
you answered your own question. walk away.
you're not that into this guy or you wouldn't have so many doubts or be making lists of reasons why it won't work. the kids are a very small part of the disaster equation for this relationship, distance & sharing him are your real enemies, are you willing to move? and if he has kids he'll resent you if you come across as competing for his time against his kids.
for me personally: if i was madly in love with someone it wouldn't matter if they had kids ( my current mate does not however), and if the kids were his priority, they'd be my priority too, I don't need all the attention to feel fulfilled in a relationship, and I'm confident & self assured enough to know i could "deal with the ex" so bring it on.
no, no, no I think people misunderstood. What I mean is when I stand back and look at this from a purely cold and practical point of view, there are many hurdles. What I'm saying is I see them and acknowlege them. I'm not blindly stumbling down a relationship alley unwares.
Actually, if it looks like it would work then I would move I have no particular ties to where I am now.