What is bad about your MLCer? Is he a bad person, or is his behavior bad? Are you labeling his actions (doing) or who he is being? We are all human beings who sometimes do bad things. MLCer have low self-worth; were we to ask them whether it is their actions or themselves that are bad, most would say they are bad people. Being bad people explains their bad actions; many will use this as a justification for their behavior--that's just the way I am. They want you and the rest of the world to confirm their badness by agreeing.
A poor upbringing, low self-worth, history of bad relationships, addictions, poor luck or poor choices may be reasons for bad behavior, but reasons do not make excuses, nor do they mean that a person is bad. Your married MLCer may be cheating with someone who is also married and who may be an MLCer; the OW or OM may simply be going through the same emotional angst that your spouse is experiencing, someone loves the OW or OM. It's easy to dehumanize them.
Standers often demonize the OW, projecting the MLCer's sins onto her. OWs are responsible for their choices, but so is your MLCer. Both are known for lying, manipulating, stringing each other along, breaking promises, cheating etc. It's understandable, you are married to your spouse and want to continue being married; you love him. Love does not require forgetting bad behaviour, but this is not merely about Agapé--unconditional love. The Eros type of love has Agapé as one of its components, but it also contains sexual and erotic love; these are conditional and rather than being specific types of love, they are merely components of Eros. Sexual attraction can also exist in the absence of Eros. It is the conditional components of Eros which you are trying to regain or maintain. How can you love someone who is treating you badly? The common tactic is to project more blame onto the OW. But she is not a demon and he is not a saint.
Review the Stages of Victim Development as well as the Steps Toward Reconciliation and Healing Trauma.
Wrong was done to me, I did nothing wrong.