Using gay and bi as an insult

Am

So today I was in my bus line and this year 9 girl (btw I’m in year 10) went ehhh that’s so gay so I went kinda light heartedly no homophobic comments here. She then went shut up so I went I’m bi (let’s call her Betty) then her sister went no one cares if u have nothing nice to say don’t say anything at all. Then another girl said something can’t remember but like did I say something wrong ?!?

Last year when I was outed there was this guy called marlon and whenever I’d say something he’d say well ur bi ur gay or even if I didn’t say anything he’d pull a face to say as if he is disgusted with me and walk away I’d just feel like shit that the fact that I like girls and boys is used as an insult, it would really get to me