What do I do? We are too proud to admit our feelings?

well from what you told us it seems like he is still caught up on you, he may have a girlfriend but it seems clear that he still has feelings for you, it is hard to say why he has been picking up on these bad habits maybe he feels like he has no control or misses you and needs something to fall back on.drugs or drinking can often take u away from reality so maybe he is trying to escape from pressures of daily life.I would forget what your friends say forget what people at school say everyone puts things in there own point of view. the time has come to sit down and talk to him really talk to him.If you still have feelings for him tell him and tell him your concerns and feelings on his new habits.ask him what he wants does he need more time? ask him why he is acting strangely and talk to him until you both understand where each other is coming from.tell him that u need to know whats going on because u don't want to hurt him and u don't want to get hurt.now isn't the time to hold things back let all he cards out on the table then see what happens from there its hard to make a decision now follow your heart and ask yourself are u better apart or together not what u want to hear but what is really in your heart.