I don’t know what to do

I’m in grade 9 right now and in the beginning of grade 8 I met this girl, and we kind of used to be friends for a few weeks, but then we both just kind of drifted apart, she had her own friend group and I had my own friend group, but I’m not friends with those girls anymore, they treated me like a third wheel and I didn’t really fit in with them and they would tell me they couldn’t hang out but then they would hang out without me. They didn’t like the other girl for some reason and I would also say I didn’t like her because they didn’t, even though I didn’t know her that well, and I feel so bad about it now, even though I don’t think they told her I said that stuff because they also said stuff like that, I still feel really bad. She used to hang out with us but then she stopped, but she was still really nice. I remember I walked out of my class when the bell rang to go to my other class and she walked by me and we made eye contact. I saw her, but I was kinda thinking about some stuff and I was kind of in my own zone, so I remember just looking away without smiling back or saying anything, and I felt kind of mean, and I feel really bad. I remembered it awhile ago and I feel like I should apologize to her for not smiling back. It happened almost two years ago now and she probably doesn’t even remember it now, it probably didn’t even affect her at all, and we don’t talk at all anymore, I’m not really friends with those girls anymore. I don’t know if I should message her and apologize or if I should just forgive myself, forget about it, and move on. If I apologize I’d probably just look stupid and weird, because it probably seemed so small. If anything I definitely learned from it, I learned that I don’t want to just go with what everything else is doing or saying if I don’t think it’s right, and I don’t want to decide if I like someone or not with out getting to know them first. Should I just apologize or move on?