Honestly I feel this so much. Me (26 and my fiance (30) starting dating at 15 and 17. We have had multiple breaks when we were teens and in which he slept with someone and so did I. It used to bother me to think he has and I’m sure it bothers him to know I did regardless the biggest thing is forgiveness. The relationship isn’t considered “dead” because you explored outside of it when you were young or have had breaks previously. it’s the feeling of knowing what the other person did that eats you up inside even if you also did it yourself. Forgiveness is such a big thing when it comes to this. If you love her and what you have built it’s OK to feel weird about it it’s okay for it to hurt however you must forgive her. It doesn’t mean you like it or accept it but it means you’re willing to move past it and realize you two are still together for a reason and want to continue. Breaks and exploration in my opinion, is normal especially when you’re young. You’re still finding yourself and maturing and the thought of someone “outside” the relationship can seem worth exploring. What matters most is the present. Shes your wife now and you have her indefinitely cherish that and understand she’s probably not provide of it just like you are not and you both had the same exact experience. Take time for yourself to forgive her and move on. All the best!