I am in exactly the same position - 12 years and 2 beautiful little kids. It beggars belief. So I share your pain. I have come to the conclusion that it is a defense mechanism too. However I think it is to shield themselves from the guilt they are feeling. This would also explain the tirade of 'bad things' I have supposedly done over the entire course of our relationship most of which are exaggerated or taken totally out of context to justify.
