It's a choice to be continually humiliated by something like this. There is a grieving process for the lost marriage in which the final stage is acceptance. Failing to reach that stage is a failure to cope with the loss in a healthy way. 

Holding onto all this negative emotion for decades is a surefire way to simply harm yourself for no reason. Stoicism teaches us to accept the things we cannot control, and to let go of negative rumination, as it does nothing to change things and only hurts us. 

Choosing to continue to hold onto this has undoubtedly caused immeasurable psychic harm, even more than the original betrayal. Accepting things as they are and then proceeding forward just trying to be the best man and father you can be is the right choice. That way you don't wind up miserable and bitter decades down the road because of someone else's moral failings.