Most Helpful Girl
People who are hurt do things they normally would not do. You leaving him bruised his ego, and it's hardly ever pleasant to know that your ex gets on with their life. You spend a lot of time with other guys now, and even though it is harmless, it is poison to your ex-boyfriend's ego. So he makes up bad things about you in order to make himself feel better.
If I were you I'd probably let it go for now. By apologising to your mother he sort of already owned up to the messages. Maybe it was a lesson for him and he won't do it again. So for now, I'd let it go. BUT if he does something like that again I'd consider further steps.