Nikkle,
It sounds as if he is testing you by locking the door. He got just what he wanted when you slipped the note under the door. Try to avoid reacting to these childish antics. I know it can be tough when you are in the midst of such chaos (I speak from personal experience).
Do your own thing for a while and let him know that you will be around when and if he is ready to have an adult discussion.