As a teacher, could I get te sack for...?

calling a student an idiot after he (every day) and after complaining about the situation several times, continues to har and make obscene gestures in my window at me. Sometimes during lunch he bangs on the door, or comes in to try and intimidate me. Today, after having a horrible lesson and being hit in the head with a bottle, he and two other guys just caught me at the wrong moment and I started shouting at him. When one of the corridor attendants came over, I asked them to "get this idiot out of here". The dinner ladies etc understood that I had a right to be angry. However, what if complaints are made by the parents. Could I be in serious trouble for that?