I read what you wrote about on ngs post regarding how you felt that your husband's infidelity took some joy away from your sons birth. And that statement was just so heart breaking.
Infidelity is awful. It is truly the worst thing one can do to a committed partner. I do not think it is forgivable. I think that when a person is unfaithful it is a sign of that persons selfishness and weakness. I read from posters in piecing and even when the WAS is remorseful, it is a difficult path to navigate. Personally, I don't think it is good for ones soul to be with someone that is unfaithful.
Many people blame infidelity on some sort of fog or mlc that the walk away spouse is in. I don't think that's what it is. Like I said, I think it's a selfishness and weakness of character... I do think the LBS enters some type of weird fog though. A fog that makes them think that someone that is capable of this type of betrayal is worth wanting back.
Would you ever date or marry a man that was capable of cheating on a woman that was pregnant or had a new born or small child? I know I wouldnt, because that says something is seriously wrong with him.