I think you won't know until this plays itself out. You'll likely come to a conclusion that your choice was good or it was poor.

I'm 5 years older than my spouse. My nephew is 14 years older than his spouse. Who knows? My relationship is 21 years and my nephew seems happy as is his wife.

I'm sure we can all think of relationships that turned ugly regardless of age. But I do think a generation difference is a lot. There's much to overcome. Kind of like him liking the Backstreet Boys and you liking Lady GaGa. Moons apart.

Good luck with this and be good to yourself.