I dunno about some of the advice given. A good personal relationship will outlast the good looks and crazy sex (and for some of us that ship sailed a decade ago
). Twenty years' difference is huge early on, but becomes less as you get older.
I am curious to know why you think this relationship is bad for you. I'm sure she will get some good-natured ribbing (cradle robber, cougar, empty nest syndrome). Legion's question about her kids is the biggest issue I can think of. But they must be old enough to not think you would try to be their new father.
I'm with Geronimo on this one. So why would she be a bad life choice if she makes you happy?
You may spend the rest of your life wondering "what if...?"