Sounds like you have gotten some wonderful advice. The worse slap in the face you could do is to not just say "her looks are fading", but LEAVING HER FOR SOMEONE ELSE is like kicking her when she's down. It's one thing if you're un happy and want to leave it's another to make her feel like she's been "replaced".
In my opinion Dawn hit the nail on the head with this one:
We women can be pretty perceptive when it comes to our man and it sounds as if your wife already senses that something may be wrong and that is why she would over-react on the phone. If you love her, it sounds like a crucial time to show her that she is still your "babe" and not your "old lady" by courting her again and by looking at her like you would look at that young hot co-worker
There is a 13 year age gap between my boyfriend of 2 1/2 yrs and myself. So if I'm 24, that doesnt make him 11
He's NEVER been attracted to younger women, and I'm the first person he's ever dated that is younger. In fact if I get jealous it's usually over a great looking "older" woman. I dont mind when he goes out with friends to the "teeny bopper" dance clubs, but I wont let him go to an upscale bar where alot of hot, older, divorced woman frequent. My attraction was not money or monagamy as it was earlier suggested, there was just a chemistry that worked regardless of our age, and a maturity emotionally that was hard to find with men my age. That has always been MY attraction to older men. And yes, I've thought of leaving, everyone does at some point, but never for another person. It's hard enough to hurt someone by leaving, it's another to "replace" them