You're nuts. The day will come when she is in her 50's or 60's (or sooner), and you don't want to fuck her anymore. But you'll be balls deep in the relationship, emotionally and financially, and possibly with a kid. So you're stuck with a granny instead of the younger gal you may well be able to get (assuming you don't fall apart as you age, too). Yes some women age well, but not so many.
I dated a woman a decade my senior a handful of years ago. I though she was a couple of years older than me, in the 'couple' sense. I just about fell off my chair when I discovered her age. IT HONESTLY WASN'T A PROBLEM. She was fit, didn't smoke, had no kids, looked young, and drank but wasn't a raging alcoholic. The age was never a factor... Most people simply didn't see much of a gap. Eventually it ended for other reasons.
If it would have worked, the age wouldn't have been the problem...
As far as the other folks here saying, 'My god, what happens if she starts looking wayyyy old?'. If it's that big a deal to him, he's on the TERB. He'll figure it out, or he could cut bait and run (Assuming he's not father #3). In the case of the OP, 2 kids with 2 fathers. That would give me serious pause. I feel confident that I could be a father (sooner than later), but I know damn well I'm happy being nobodies daddy right now. If I ran I would have run at that!
To the OP: Yeah, she's older and she has kids. If you love her, and she loves you, and there are no other red flags, and you're fine with the her age right now and the kids (that I'd have a hard time getting over), don't let anybody scare you into running. It's your happiness! If you're happy, be happy! It's rare enough. (Though, like all men, you should be sensible and cover your legally ass when it comes time for that.) If she happens to age poorly, after a decade of mutual happiness, and continued happiness about everything but her aging, what have you lost? By then it might not be that important to you, and that is a bridge you can cross then.
For all of the guys saying 'go young', I say, 'go reasonable' and and focus on being happy.
edit: Though kids and the lack of condoms give me serious pause.