Bf’s ex laugh react at our family photo

So like, my boyfriend and I broke up for 6 months about 8 months ago. During those 6 months he started dating a girl. I asked for the break up. So I couldn’t really be mad at the fact that he started dating other people. While they were dating I reached out to him and told him I wanted to get back together. It was hard, but he did. I recently posted a picture of my son, my boyfriend (Baby daddy) and I. His ex laughed reacted at it. I’m not even friends with her ! I asked him about it and he said that he thinks she’s just jealous but now I’m kind of getting paranoid. What if she’s laughing at me??! Like....she’s laughing because I don’t know something 🤷🏽‍♀️what do y’all think?