You were the reason for the breakup and you don't like yourself for it. You've done some things in that relationship that you feel guilty and are deeply ashamed about. You need to work on forgiving yourself. The fact that you are caring and feeling guilty, and empathetic about this after the breakup, means that you can empathize with people. There are people out there that can't do that. Figure out the lessons that you need to learn, heal and show up better in the future. You have to live with you for the rest of your life. You might as well like yourself.