First. His LTA was not a mistake. A mistake is something you do once. Could be an error in judgement. Or forgetfulness. A mistake is not something you do and KEEP DOING for 7 (or 13) years.
About the anniversary. My view is that my M ended when WW jumped in the sack with OM. In my mind to celebrate an anniversary is to celebrate something that has been continuous over many years. My WWs LTA ended that. Now the *anniversary* celebrates nothing.
I struggle with anniversaries because there is this expectation that it should be celebrated. If someone died I would not celebrate that date. I might instead give some silence and thought to them and remember what I lost. Having a nice dinner and a party would be completely inappropriate in my view.
Recently we passed the 40 year mark of the date WW and I said our vows. WW wanted to have a party. I was absolutely against it but she did it anyway. She seems to have this attitude of *we had a bit of trouble there but we made it*. Maybe she made it but I sure did not. I told WW I would rather she not have this party but she did it anyway.
It was awkward. I just stayed away from as much of the action as I could and drank beer. Even though I have worked hard at not letting what WW does not bother me. I was still triggered by the whole thing. I hung out with the men and drank beer and tried to not think about what we were supposed to be celebrating.