If this isn’t too personal: maybe inquire about why she chose not to wear undergarments. Why she felt the need to unbutton and unzip her pants so publicly? I agree with you. Crop tops and no bras shouldn’t be sexualized because it’s hot out. But there are plenty of crop tops (the majority, actually) that don’t show off under-boob. Approach this subject gently, maybe even using some of the things you wrote here.

As for your boyfriend I think you should be supportive of him. He voiced an opinion and while some may disagree, it sounds like she blew it out of proportion. Honestly, at this point, I would cut Molly off. She slandered your boyfriend’s name online and seems to be a person attracted to attention and drama.