boyfriend: a cheater/liar or just talk

I'm in a new relationship and at first it was going great. He treated me right and everything, the whole nine yards. Anyway, one night we were hanging out with some friends and we were talking about past relationships. He stated, "I'm always the one to be chested on, but I have never cheated. I am faithful." So as the week progresses a few of my brothers friends, that are like brothers to me, tell me, "He's cheated on every girl he's ever been with."