Confused and hurt

I had a boyfriend who I had to take a “break” with and it’s just been stressful. When we did date his ex(who is also with child) started talking about how she wanted to fight when she was done so I was like ok I’m just gonna mind my own but it’s like she’s still talking and I still have to sit next to him in some classes. But we only took a break because I told him and he did nothing about it. I just don’t know what to do