It sounds like he may have a problem, but unfortunately you can't force a person to admit to having a problem and then having them fix it - without admiting it to themselves first.

Does he have any other friends? Perhaps getting him to meet others will be a good thing for him.

Beyond that: If it bothers you, and hurts you emotionally - YOU need to leave for your own wellbeing. I'm sad saying that, because it sucks... but its ultimately you needing to take care of yourself FIRST.