Marriage (Rant)

My dad told me that he’s going to marry his girlfriend (the one he cheated on my mother with). My parents have never been married, they have been with each for 18 years when he cheated on her. I remember the day they told me they were going to separate like it was yesterday. Sometimes I feel like I could have changed something. I could have told him that my mom and I loved him so much or something that would have made him feel guilty and break up with her (the girlfriend). I will never know. What I keep wondering though is how is she better than my mother? I have met her a few weeks ago and I wasn’t a fan to be honest, and it’s not because of the circumstances but because I genuinely don’t like her very much. I know that it’s also my Dad’s fault but I hold her more accountable for the way my life is. My mom has had depression ever since the separation and I have to live with her bipolarness. It makes me miserable. I just feel like I had to talk about this to someone.