Ex best friend trying to make me jealous

Sierra
So my boyfriend and my ex best friend work at the same place and today I go on snapchat I still hav my ex best friend still on my friends list just because. Anyways she posts a story.. I look at it.. It's a picture with her and my boyfriend just chillin in the back of the restaurant and the caption thingy has this: 😘😘😘 and she knew I would look at it so that's y she put it.. I'm just so upset and I confronted my boyfriend about it and he says they didn't do anything and that he didn't even want a picture taken. In the pic u can c that he's all blurry cuz he was tying to get out of the way so I believe him when he says he didn't want a pic with her. I'm just really annoyed that she did that to me.. I'm really upset and idk what to do about it. Ik she wants a reaction out of me but she's not gonna get one. Anyways is there anything I can do to just get back at her just because I hate this little slut. Please and thank u😊