Family thinks I will go back with cheating ex.

I went through this with my sister. Years of her leaving him then going back. Years of "I'm done! I'm never going back! Aren't you proud of me for leaving him?" and then promptly going back. Of course we stopped believing that she was truly done with him--all her past behavior showed otherwise. But oh boy did she want us to praise her to the moon and back every day for the couple of weeks she'd be crashing with one family member or another during one of her "I've left him!" periods. And she would be extremely upset with us when we wouldn't. Conversely, every time she went back and we failed to show the appropriate level of enthusiasm for said relationship, we'd get yelled out for being unsupportive. It got real old, real fast.

In fact, she only truly was finished with him when he was sent to prison for 2+ years for a drunk hit-and-run.