Hey,
Anyone who reads this thread MUST picture the two profile pics of the babies from the first two posts as though they're talking back and forth to each other.
It's really humorous.
Seriously though, picture it that way and you'll laugh. After that, dating an older guy or what ever else stresses you will be put in perspective. If you're happy with it, be happy. If you're only a couple years older then his kids, great, you'll make some friends. Chances are the guy is with the woman he lives with but obviously somethings missing there that is making him go else where for love (Don't count on him leaving her completely anytime soon).
I'd say stick with him for now. Your parents are going through a split up so you are probably feeling some kind of void that needs filling too. There is definitely no one better to fill the void that divorcing parents leave in their children, then an older man.
If your happy with him, don't worry about it. Just be safe, don't get pregnant, and live up this fantasy world for a while.
Hope every thing works out,
Julia