I am so furious that this happened to you. My first instict was to madek assuptions about your friends based on age. I'm 26 and mid/plus size and have posted pictures on instagram that are pretty boob-heavy. I've never gotten comments like that, and I wonder if some of that is because I came of age in college during Me Too, etc.
Because that's an assumption, I thought more likely it may have to do with those specific friends. I agree with the other commenters that you should remove them from your Insta and use it as you want. Be "bold" with your life. The people who are calling negative attention to your body don't deserbe to get to have any of your focus. It's harder said than done with friends, but your online platforms are a space you can (somewhat) control, and you deserve to do so.
Back on the generational point, I remember getting weird comments about my breasts but only from older folks. Big boobs (and little boobs, etc.) are all discussed, at least by women, as awesome and beautiful. Again, at least in my circles. You are not wrong in the slightest here. Your body is a vessel for so much good (and it's fucking wonderful), and you deserve more days like this.
I'll add you on Instagram if you choose to publicize it again and go through all those comments with graceful, firm responses if you'd like <3