My boyfriend's ex-girlfriend went home and got married, and kept texting her boyfriend about how much she regretted and how painful she was. What should I do?

You are a little weak! In fact, there is nothing wrong with you from beginning to end. Why did you put up with all that pain? Why mention him and her to find some reasons to comfort themselves? There's no need! You are his girlfriend, she is nothing, even if there is a past, it is the past, he has long since stopped loving her, just out of help for an ordinary friend. But if you continue to help, you tell him that it is unfair and harmful to you. I hope he can take a stand and gradually alienate her.