Most Helpful Guy
I don't know how involved your mom is in your relationships and if she bans you from seeing him or anything but my advice is if you really have feelings for him you'll move on or you'll make him realize you made a mistake of leaving him based on your mom's decisions.
My ex's mom didn't like me for a couple of years but we still worked and eventually she came around because I proved I wasn't anything like she kept saying. We aren't together anymore but that's besides the point and nothing to do with her mom lol.
Most Helpful Girl
But if it's over, why is she still talking badly about him? Doesn't she have other things to keep her occupied? Just switch the topic or stand up for him, usually clarity is obtained with purposeful communication... does she have valid or invalid reasons for you two not being together? I am happy that I listened to my mom on this one guy I liked, she was really looking out for me but at the time I was too vulnerable to see that and got angry with her. Sometimes, only you can give yourself the best advice, as you know the situation best. I would say if you weigh the pros and cons, giving priority to what is needed you can come to the right decision. For now, it isn't her business to keep talking badly about this guy that you are no longer with.