storytime! should i apologise?

how to tell a guy you never dated that you miss being friends?

j= guy a= my friend

so basically i was eating lunch with my friends then another one of my friends from primary came up to me lets call her a

a said do u know j 

and i was like yeah but i've never spoken to him in my life, j was a kid in my class he was nice but we've never spoken 

a said he has a crush on you 

i said thats weird we've never talked 

she said i gave him your number 

i was like girl what u could've asked but ig thats fine. like two days later he messaged me saying hey are in in the class group chat i said no ( i've never been in a class group chat no one ever invites me to any ) so he added me and we started talking on the gc and everyone started shipping us. i was exited this has never happed to me before but i still didn't know if in liked him so we talked for like months then one day he sent me this message

so theres this girl called holly you probs don't know her anyway she's like the sweetest person i've ever met and like just seems perfect in every way but i haven't seen her in like a month and i miss her so much ive been thinking abt her and worrying abt her like ever since the end of the schl yr so idk what to do can you help

first of all, i'm flattered as a person who doesn't see much in myself, second of all, WHAT AM I MENT TO SAY TO THATTT??? i decided that i didn't want to date, just in general i feel like i'm too young, so i just said 

i don't know her and i don't know how to help so sorry

he just said dang it

we still continued talking for the rest of summer but the messages got slower then we just kind of stoped. i'm kinda glad we stoped talking because i felt like i was leading him on. but now i have two problems. i feel bad because i should've told him i knew and i feel like i kinda sorta gosted him and i generally did a bad thing. and 2...  I MISS HIMMM! i miss being friends with him and talking everyday i don't want to date i just want someone to talk to someone like him.

what should i do?