Why does my mom hates my husband but love my ex?

It’s a weird situation my husband is the sweetest person you can ever meet. He’s like a cute tiny guinea pig. He doesn’t like to scream he does Everything a husband would do plus more he teaches me and my kids new things 24 seven right and then he’s literally starting school this year so he could have a good career in four years so I don’t have to work anymore. That’s exactly what he said. He said I don’t want you to work anymore so I’m going to go back to college and when he first moved in with me, everything was good like he made sure that my mom had things that she wanted like cigarettes or if she wants to use his car. He will let her use the car without him complaining like he’s a wonderful person to be with, and I’m glad that I met the right one but my mother just don’t like him. She complains about how he walks how he acts she complains that he bought himself a cheeseburger and fries because it was food at the house for the kids that he was going to cook, but he didn’t want the food that was cooked so he got himself some food and she basically called him a stupid person because he should’ve fed the kids fast food, and he shouldn’t have ate She’s always calling him weird she’s always saying how he talks about her behind her back, but that’s not true right now. My mom and my little brother is staying at my old apartment and guess who’s paying the rent my husband my husband vented to me about the situation on why my mother doesn’t like him even though he do so much but yesterday my mother was having a very nice conversation with my ex/abuser. She was smiling happy and she was trying to tell me how conversation went she follow my abuser on social media and she followed his dad on there one day she told me how much my ex miss being with me and she asked me if I’m ever going to go back with him. I told her no, and I do confront her when she tries to be very disrespectful about my husband, but my husband is in a situation if he don’t know if he should keep helping her