It's an old story. As my pre-poster said, there will always be somebody like that. The lecturer that you spoke to is actually right: don't worry to much about this person. Supervisors aren't stupid, they have to deal with different students all the time, an arrogant and grudgy type isn't seldom. (It actually has nothing to do with science...) Instead of wasting your energy on this a******, concentrate on your strengths and your own path. Such people try to bring somebody else down just to compensate for their own insecurities.