I remember when I traveled down that road of anger. It always ended with me, anger at myself for all of those same things you said, staying to long, coming back, being disrespected and lied to over and over again, I took it, I believed the unbelievable. YET I somehow still expected normal behavior from someone with abnormal behavior, thinking and logic.
I think once you are totally resolved that the relationship is really over and you can fully let go, their behaviors no longer shock or surprise you because it won’t matter anymore, you will have reached full acceptance and your focus will be on the future not the past.