Ah I see, thanks for the clarification.

I think many of us can relate to struggling to identify the reasons we did something, small or big. I know I still do for things that happened several years ago.

But personally, I think you can still hold your ground if that trigger ever presents itself again, even if you never know why you did what you did.

Because you feel guilty for what you've done, have held yourself accountable, and I think, understand the hurt you've caused. ( I say think, just because there was no mention of it and you seem like you have a good head on your shoulders).

If that trigger were to ever appear again, try to think back on that if it doesn't already instantly come up, which I think it would.

I do hope that you come to understand on some level, if not completely, why it happened.

Honestly, it sounds like something a therapist would be perfectly suited to help with, but I understand not everyone can afford it and maybe you don't see it as enough of a problem to seek therapy for it. But that's always an option.

Otherwise, not sure how else you can find out why you cheated. Sometimes it just clicks after reading or watching something that resonates with you, and you're somehow able to connect that to a past action. I know that has happened to me.

You do mention though that you thought in the moment that she was probably doing the same thing. Was that a thought that just occurred to you while it happened, or something that was lingering in your mind before then? Maybe not exactly that thought, but something similar? Idk, just reaching at this point.