Social media makes me insecure.

So last night I was on Instagram and discovered that my boyfriend was a major fan of one of our friends pictures. She is a small, super cute brunette, that's probably a size 2 and absolutely the complete opposite of me physically. We're probably the same height, about 5'3", I'm brunette, with green / blue eyes and I am a size 4/6.....he liked about every picture she has posted, either bikini, selfie, beach photo etc....I tried talking to my best friend about it last night and she said it's probably because we look a little similar....I don't give a flying fuck if we look similar, it hurts my feelings because she isn't some girl who is living states or countries away, she's right at home and they're friends!! I just feel extremely insecure about this for some reason. Like maybe he had a thing for her at some point in the past, and wishes I was her. My mind wanders a lot and it gets me so riled up, it's scary. But I just need to know I'm not alone or that these feelings aren't ridiculous, even tho they are🙈does ANYONE else get this way too?