Should I say something?

A little while ago this girl name Kate came up in my relationship with my boyfriend. I was a little skeptical about her because I never heard of her before until I saw her tagged with my boyfriend in a comment which is nothing. So I talked to him about it and cleared it with him right? Then later I see that my boyfriend posted a sweet picture about me on Snapchat consisting of how much he loved me and how I was special then Kate’s friend remarks “except Kate” then I got furious because I didn’t know what the hell this was so I could use an opinion for that if possible please? But I confronted him about it and at first he denied he got a message like that then later said Kate’s friend did that as a joke because my boyfriend told them two about how I got upset the first time.. therefore I found it disrespectful so what should I do?