As an atheist, must I feel bad for cheating on my pregnant Christian wife when her past is just as bad as mine?

I'm an atheist man and I've been with my born-again Christian wife for 8 years(3 years of dating, 5 years of marriage). She respects my lack of religion. We have a 2 year old daughter together and she's currently 7 months pregnant with a boy. I am having an affair with two different women and I know it makes me seem like a loser but the reality is, my wife is a tramp. Sure, I love her, she loves me and she's never been unfaithful to me but her history really tears me up for deep personal reasons. My wife has a 10 year old son(my stepson). Her son's father is a married PASTOR who betrayed his God-fearing devoted wife when he committed adultery and impregnated another female. I tried to look past my wife's history being that this happened before she met me. I tried to look past the religion issue. But I can't help it. I NEVER forgave my so-called Catholic father for cheating on my mother and leaving her for his . My dad left me, my mom and my 3 siblings struggling, poor and broke. My mom claims that her faith in God has gotten her through those rough times but I stopped practicing religion once I went away to college. Therefore, if my wife finds out about my cheating, I hope she does the "Christian thing" and forgives me. Did she give a damn about her religion when she got knocked up by a married pastor? I have no respect for homewreckers. I don't respect the who stole my dad, I don't respect the s I'm having with and sadly, I BARELY respect my wife. But rest ured, I DO love her, otherwise we wouldn't be married. Spritually speaking, am I wrong or do you understand what I'm feeling?