Part of recovery for us is forgiving ourselves for staying in and putting up with (often) appalling behavior. She showed you numerous times who she was. Aside from the drinking she was cheating. You gave her multiple opportunities when you should have ended it. As an adult, you don't have to be taught how to respect someone to know what respect is. You don't have to be taught to be honest to know what a lie is. Certainly her upbringing has molded her, yet that can become a codie's excuse to continue on in a relationship by excusing behavior due to "uncontrollable" bad parenting, and poor family relationships.
Your roll in a situation like this becomes parental. Its not a fulfilling, or a healthy relationship.
. She gets to hurt me emotionally and then move on without a second thought or feeling any kind of remorse. You don't know what she feels. Its better that way. No point in projecting on her what you think she thinks, or feels. Perhaps before you did, she realized it wasn't going to work. Even if you knew she was sorry it doesn't really change anything. Its not that she GOT to hurt you, you allowed her to. First time shame on you, second time shame on me kinda thing. Its important to recognize your part in it lest you feel that you were her punching bag with no alternatives.
Codies dismiss red flags, and will take loads of unacceptable behavior. Then be upset for the lack of caring by the person who does it. I have often reflected on past relationships in which I was treated badly and forgave, forgave, forgave, only to live another miserable day with them down the road. Who's the crazy one them or me? ME.