Getting Dropped By Friend Once He Gets A Girlfriend?

I think that you already have the answer. You should not let anyone use you for their disposal the way this guy has been using you. Just step back and when he calls and want you to do something, just tell him that you are busy or is going out and cannot talk or make up something to tell him. You see, this is giving him a dose of his own medicine and then he would see how it feels to dismiss a friend, the way he's been dismissing you for so long.