text: He will eventually see how bad this girl treats him, so let him learn by his own mistakes.If you tell him anything negative about her, he may get upset at you!  Just keep being his friend and once him and this terrible girl break up, you can express your feelings for him then if you feel the time is right.  Otherwise, just be yourself and he'll realize how special you are, whether it's as his best friend or his girlfriend!  \nGood luck!