Honest opinion please

How would you feel if your boyfriend had told you he sometimes sees other girls in public and finds them attractive? My boyfriend told me this today while he had some questions about me coming out as bisexual earlier this year. I don’t know if overreacting and being really insecure but when I’m with him I don’t feel the same way about anyone else, I really honestly just love him and see him attractive no one else. I’m just kinda hurt and caught off guard from what he said. It really did bring out a lot of insecurities of mine as I did gain a tone of weight during this whole pandemic and always getting told I’m a bigger girl and just so much more trauma I’ve been through that he knows, but maybe I’m just overreacting and need to work on myself? Please be honest I really want to know how everyone else would feel if they were in my situation or just any inputs.