"Don't be deceived, bad company corrupts good manners"
Sometimes it is up to you to decide who will define you. Of course we decide our own actions for ourselves. Yet it is true that those people with whom you surround yourself with are the ones who most influence your mannerisms and thought process. Sometimes it may be necessary to bid adieu to those whom you know are negative influences. Or if this isn't logistically possible, at least decide how much time you should give to them. Being there for others if it harms yourself isn't healthy. I think we have all learned this at one point in our lives. The Lord teaches up to support each other and give ourselves to others (John 15:13), but He also teaches that we must better ourselves before judging and nit picking others (Matthew 7:3). In friendships you become the judge of both yourself and your friend - since they depend on you to help them make decisions and care about your opinion. Be sure that you are in a healthy place individually before you try to go around and save the world. Just some words for thought.