Flashback of my partner's infidelity

I was wondering to myself if I am the only one who experienced being deceived by my partner. We're married for 6 years, we have kids but in the mid years of our marriage my partner cheated me twice. I just recently knew that a one night stand happened between my partner with the unknown stranger. It really hurts than being caught with all the recorded flirting conversation with other person aside from me. I forgive my partner once but how about having a one night stand? I forgive but I never forget and it keeps repeating on my thoughts every now and then. And it adds up with my depression and anxiety. How to overcome this thoughts and feelings of being cheated and broken?

It's very hard to forgive... I can't say much on that topic.. but once you forgive it's almost like saying it's ok and get ready for out to happen again. What caused them to stay... Was that conversation ever discussed!?? Not just why but how come?