Generally I would advise against telling your wife
anything about your past relationships.
IME... Women often read things into what comes out of our mouths and that can become skewed to say the least.
..... and (I know I may get flamed for writing this) Women are more emotional than men and often get hurt by something that wouldn't have any effect a man.
So don't do it would be my final advise.
It's all about looking after your relationship and you're not being dishonest by not telling her.