DB does not condone affairs by LBS spouses. That isn't an opinion. That is exactly what the moderator said. And as someone who agrees with the basic provisions of DB, I will repeat it.
The fact is that MMB is doing something that is not DB and wants validation. Sorry, it doesn't work that way. Besides she is not being honest with the object of her affections. That is not DBing. So what MMB is doing is wrong. If she wants validation she should go to myhusbanddumpedmesoIamhavinganaffair.com. MMB even admitted that this current relationship started poorly. It is time for MMB to step up to the plate and be honest with this man. One of two things will happen. Either a) he will dump her immediately or b) he will prove all he is doing is screwing her. No matter what, this is not the way to build a solid relationship or improve a failing one and MMB has said as much.
Come on, MMB, do you want to save your marriage or not. If so, having an affair is wrong. Why? Because it is a lie.