I also don't quite understand how something from +14 years ago came up, and how or why it is relevant to your present day life. Some detail might help...

Since you never had any inclination to experience a FFM 3-some, why do you feel robbed of a wild time with your wife? This is a question you need not answer to me, but for yourself, as it may be the clue to getting over this very painful hurdle...

I'm sorry if this sounds unhelpful, but I honestly don't see the problem. Why drive yourself nuts over a past that was none of your concern in the first place?
The answer to this question will also no doubt be helpful in your healing process.

You've had 14 yrs of sex with your wife, so whatever inexperience you may have suffered from in the past has been dealt with by now.

I'm really sorry you are hurt by this info, but IMO, you have to realize that her sexual past really is none of your business. It was before your time and in reality its irrelevant because it doesn't affect you (she never gave you a disease) except for in the way you are allowing it to affect you right now... You have to learn to let go of her past, its hers.

Some food for thought:
If your wife shared this news with you while dating, she would have never had a snowballs chance in hell to walk down the aisle with you, and probably knew this, so was smart enough to keep it secret. If your marriage is good and you are happy, wasn't it a good thing you didn't know beforehand, because the past 14 yrs wouldn't have happened?