AIO friend took photo of me and laughed

This is not the normal "goofy" photo, silly blur or angle or face, but it is in the same realm.

I went to a small DIY photography event yesterday & invited 2 friends (a couple). We were taking photos in 3rds out the wazoo. It was really fun.

My friend took a photo zoomed in of my backside as I was bending over to take photos of flowers. All shirts are kind of low cut right now, and I was wearing low rise jeans. It was basically just a photo of muffintop (for clarification, I do not have much, so maybe they didn't feel it was mean because I am skinny?). They laughed really hard and the other friend said some comments that were basically saying it was fucked up or something like that a few times (W), and I was in shock and only commented on it in a joking/passive aggressive way slightly later, like "ur phone needs to be bricked and all the files deleted" or like "ya like you taking photos of my love handles or muffin top or whatever the fuck it's called" in a "joking" angry way. Obviously it is not a joke as I am posting here. I am not proud that it is hard for me to be direct as soon as a moment happens. It is a really bad habit of mine but I have a processing disorder and general avoidance issues.

It is the next morning and I am crying about it because it makes me feel like it stripped the automatic safety of being with friends, like it was a betrayal. I am wondering if I should text them today and put this into words and ask for an apology. I know it was a weird thing to do, I just need to know I'm not going crazy. This feels so retarded because it feels like something that would happen in highschool, not at 21-24 (The age difference between the two of us).