I am my wife best and only true lover why do I feel scared to see some1 she had sex with 1x as a teen?

We have been maried for 10 years . Have 2kids. However last year there were some flurting between her and a co-worker via text messages.and was sent to my work email for me to read my an aynonomous co -worker. She said it was a lapse of jidgement, nothing happen. But since then I have been on edge about ever male new or old.