A good guy friend of mine starting to act like a d$&k!?

This good guy friend was a sweet nice guy but I turned him down but were still buds but ever since he lost his virginity a couple weeks ago he has been acting like a total d$&che and it's kinda awkward being round him now :P and he keeps bragging how he lost it before his 16 year old older bro and it's gettin on my nerves he used to be so nice now he has turned into a extreme creepo! Btw he is 12 or 13!!!! And I am 13 so i never thot I would hav to deal with sumthin like this! He was a quiet shy nice guy that didn't have many buds and I liked him as a bud then and now :/ HELP!!!!!:((((