Your worth is not determined by him but by you. It took me a while to get it. MLCs are attracted to OW for how they make them feel not for what they look, it took me a while to understand that concept but that's true. They love the feeling of having their ego being stroked and having the fantasy of rewriting themselves under a much better light. Your are reality, she is fantasy. Usually fantasy starts to fade when they are facing reality (major decisions and daily life). The more you will fight, the more you will push him toward her, in his MLC mind he sees you as the cause of his unhappiness even if it's not true. Remove from him any causes of arguments (see the detachment thread). Did you read it? That's the basic of DB. Sorry to insist on it. I might suggest of saying anything about the texting, he is here with you not with her, don't start an argument even if you are right.
Me 52+ WH 57+ Married 20 + Piecing since 2016 (ready to give up...)