You were the one who when the time came said you were willing to take on the responsibility of another life with this person. Stop me if I 'am wrong, gentlemen, I have been known to occasionally make mistakes. If you honestly evaluate the scenario at hand the only thing that has really changed is that you both realized that the relationship you once had did not work. I'm simply saying that if she was good enough to have sex with, at least respect her and yourself by not making derogatory remarks about her. I've heard all that crap about how men need sex and if a woman is throwing it at you, you have to take it.
Children learn by example.
You are saying that you have absolutely no respect for her and that the child shouldn't either. I was always told that talking about someone's mother was grounds for a fight. Shouldn't you feel disrespected too because after all you two came together and created a miracle. Life is a miracle, whether planned or not. If you have unprotected sex be prepared to suffer the consequences.