Help pls..my friend bluffs and cheats a lot..what to do??

this roommate of mine has this habit of bluffing a lot..he exaggerates everything..he knows we dont buy into his stuff but he still continues..he lies a lot too..there was this one instance where he lied about this MBA college admission interview..he told us that he was going for the interview but was spotted watching a movie..he came home and told us he had been rejected at the last round..there are many more such instances..this is not only my complaint..everybody in my college has the same opinion about him..i have told this to him many many times..to change his ways..and how people call him a dumb@$$ on his back..my other friends now tell me that talking to him is useless..they say he has no conscience..he has cheated them too many times..got money outta them..but hes been with me for the last 4 years..we still have 3 months to stay together..i have see him everyday..cant face him like this..what should i do??pls help..