Hi

You need to do a few things to improve upon from the present situation.
As you have written, you are idle, feel marginalised and needless to mention a bit frustrated also.
As a first step to reverse the situation you need to talk to your boss. Request him for a personal meeting and tell him that you value his feedback in order to bring in desired behaviour modification in you. Listen to his feedback without reacting to it . Take notes if necessary and recall situations from the past to test the feedback. This way you will get the clues wherein you need to improve.
Secondly please do not be rude to others irrespective of the fact that they are rude to you. It is a reactive response and it will make thing worse. Reply to all in your most polite manner. Make it a habit. Done consistently over a period it is going to change everybody's view about you behaviour and I am sure no body will ignore you.
Best Of Luck
Mohan.