Am I being silly?

My MIL texted asking when my baby's first swimming lesson is because she wants to come. I totally get it, and I said she could come, but secretly I'm irritated. It was supposed to be something special between the two of us, a bonding experience.. and he's never been in a pool before. Now I have to worry about how I look in my bathing suit since I know she'll be taking a billion photos during the whole thing. It's kind of ruined for me. I just wanted it to be fun for the two of us, I didn't want to care about how I looked or if I'm doing a good job handling his first lesson. I didn't want a damn photoshoot for the world to see. I'm super self conscious of my mom bod. Anyone have advice or should I just get over it?