How do I get over this girl or get her back?

Okay she oviously does not love you or care about as you thought she did, if he loved you or cared about you she would never have done that. You don't treat someone you care about the way she treated you. You need to have more self respect and realize you deserve better and you will find a women who really loves and appreciates you and would not ever cheat or treat you like that. When you said without her I know not be half the man I am, you have to see that she is not making you a good man look how much you are hurting and how you are behaving, a women who made you a better man would treat you good and be a positive in your life and that would make you want to be best you can for her. This is not the case she does not care about you, I know that is hard to hear. Be honest with your self and have more respect for yourself. Keep yourself busy, so you don't think about her and you will see that with time you will start to forget about her. Time will heal you. You will find a women who will treat you better and care for you and not cheat on. That girl has no respect or love for you. Move on.