I think my best friend is mad at me and punishing me.

Here’s the backstory. We have been friends since 1st grade and we used have crushes on each other when we were younger. In middle school I moved on though because I thought he didn’t have feelings for me. In eighth grade, I got a boyfriend. We dated for a year. During that time, my friend sent me a couple of long texts vaguely saying that they liked me and missed me, felt awkward talking to me at school with my boyfriend there, and more. I feel like he wrote them so vaguely so there wasn’t really a way to outright reject him because he would sort of tip tow around his meaning. I would usually answer the texts saying that he was a really great friend and I was sorry he felt like I wasn’t spending as much time with him. Btw, I hung out with him just as regularly during this time as I did before. When he found out that I broke up with my boyfriend, he didn’t say much abt it. We have spent time together as usual. But in the past month or so, I feel like he is ignoring me. I text him about hanging out, only for him to text back weeks later saying “sorry, missed this text”. We went back to school last week and he would greet me in the halls with a small nod. I asked him if he wanted to hang out this weekend, but he said he had plans very quickly. I’m just getting a weird vibe from him. Does he think I’m coming back to him now that my boyfriend is gone? Does he think he’s my second choice, my backup? This isn’t true, but I also don’t like him like that and don’t want to date him, or anyone for that matter, I realize now that I should wait until later for that. Can anyone give an opinion on this? Sorry for such a long post. Thank you.

Update: I have now approached him twice at school just to talk to hime about nothing serious, just asking him how he’s doing and how he’s liking in-person schooling again, and he CANNOT make eye contact with me. He literally looks wherever he can BUT ME, and quickly ends the conversation and leaves. I’m planning on confronting him soon. Thank you Molly for your advice!