Shall i go with my guy friend as a date to prom or my group of friends? Please help!?

okay so basically he (my friend) had asked me to prom a couple months ago through text while we were conversing which i found kind of awkward but i said yes because i though he was a great sweet friend. about a month after that, he send me a "text" saying he got back with his ex and said he was going to take HER to prom. i did feel a little confused and i told him i understood. i personally thought it was very immature due to the fact the he used texting instead of talking to me in person because i have him for a cl. now hes asking me out to prom again which im finding it very childish although this time he asked in person, and its the second day in a row, i haven't answered him because well for 1 i don't want him to think im dumb? and 2 well i do feel bad for him because he is a good guy. or am i exaggerating/wrong with all this? i mean prom is just around the corner. i would like to answer him without looking or sounding like an imbecile. i truly need all the help i can get as you can tell. please.!