Technically, you don't say shyt like this to people you don't know that well, but I feel like she tweeted this solely for the purpose of support of other people on social media. I doubt there was anyone chastising Barkley after that terrible joke, so she needed some support.
But shyt, who knows, she may have been or knows a victim of domestic violence in the past and this struck a nerve.
To be fair, she could've just told Barkley that she didn't appreciate the joke to his face, but that's not going to stop him from making it in public. Public humiliation will though.
EDIT: Apparently she did say it to his face and he acted the way you would assume. "You can't take a joke".