Not being truthful to my wife - how bad is this?

Long story - but I will condense as much as I can...
Married 10 years, wife and I are very happy. We are sole mates, but realized a few years into our marriage that we were not really "sex mates". She has much more of a sex drive than I do - so for awhile there we did some roleplaying, which led to us dabbling into an "unconventional" lifestyle that was actually pretty exciting as it was going on. My wife was getting everything she needed, and it actually brought us closer together since we were doing those things as a couple.
Anyhow, my wife decided she did not want to do that anymore, and we went back to a very mundane sex life.
I was in a department store a few months ago, and there happened to be a display of perfume that my old girlfriend used. She and I had THE best sex together.
So, I bought a box that had a few size bottles of that brand of perfume.
My wife was surprised that I bought her something like that, but she admitted that she liked the fragrance.
Honestly, it is like Viagra for me -
I am more "ready" for sex with my wife, thanks to the perfume I bought her! It takes my mind back to being with old girlfriend.
I could never tell my wife the truth, though.
How bad is it to use the ex's perfume as a turn on for me? Even though my wife is benefitting from it??