crushing on this guy

i've had a crush on this guy in my class for nearly 4 years now. I don't know whether to confess to him since its our last year in school.

Honestly speaking, I've only liked him because of the conversations we have with each other on Instagram. We never talk to each other irl despite being in the same class for the last 4 years 🙏 I asked one of his friends whether he was single but he wasnt sure.

I thinking whether I should confess to him via letter or face-to-face. Or maybe not confess to him at all. I just chatted with him 2 days ago and he knows that i have a crush but doesn't know that its him. he keeps asking who is it but i cant bring up the courage to tell him yet!!

So, should I confess? Or any suggestions to make sure he might or might not like me? please help 🙏

(edit: update post is up!)