Breaking the cycle

How to you change something about you when that is all you've known? When part of the reason why you are the way that you are is because of what you witnessed as a child, and no matter what, somehow you manage to screw everything up that you touch? That is how I feel right now. It seems as if every relationship that I have had I manage to somehow screw it up, because I somehow have developed my mother's habits. Growing up, she cheated on my dad constantly, picked fights, beat him up, etc, so I thought that it was ok. I swore I never would turn into her, but part of me has. I cheated on Josh with Andrew, got pregnant and had a miscarriage. Then there is Nathan, I've put him through hell more than once. He's stuck by me, and I don't deserve it. I've lost his trust, more than once, and each time it's harder to gain back. He's mad at me bc I unblocked Josh from Facebook, and thinks I've talked to him, which I hadn't, since December. He wasn't starting anything so I unblocked him. I love Nathan more than anything, I don't want anyone but him and our kids. Josh means nothing to me. I have got to stop turning into my mother, she is slowly ruining my life. From yelling at my kids, to manipulating me, to ingraining into me that it's ok to treat people like I had in the past. I've got to break the cycle. I want my family!