This is exactly what is happening, in my opinion.
Why do you care who slept with your wife or what they did if it was before you met? I’m pretty sure that if she lied to you about anything, it was because she was uncomfortable with the subject matter or she didn’t want to upset you.
You will do a better job building a sense of trust if you seem like a person who is not conducting an interrogation about her sex life before you met with an itchy trigger finger.
Even if you can’t help yourself from getting jealous about this, why would you bring it up to her?
Bury this. Don’t think about it anymore. Treat her like she’s the best person in the world and she just might return the sentiment.