Crosshair Dissapears When I Right Click

Hi, I'm working on an fps game but when I right click to aim down the sights the crosshair doesn't disappear and gets messed up with the sights

here's my crosshair script:

  #pragma strict
          
  var drawCrosshair = true;
          
  var crosshairColor = Color.white;   //The crosshair color
          
  var width : float = 3;      //Crosshair width
  var height : float = 35;     //Crosshair height
          
  class spreading{
      var spread = 20.0;          //Adjust this for a bigger or smaller crosshair
      var maxSpread = 60.0;
      var minSpread = 20.0;
      var spreadPerSecond = 30.0;
      var decreasePerSecond = 25.0;
  }
  
  var spread : spreading;
          
  private var tex : Texture2D;
          
  private var lineStyle : GUIStyle;
          
  function Awake (){
      tex = Texture2D(1,1);
  
      SetColor(tex, crosshairColor); //Set color
  
      lineStyle = GUIStyle();
      lineStyle.normal.background = tex;
  }
  
  function Update (){
      if(Input.GetButton("Fire1")){
          spread.spread += spread.spreadPerSecond * Time.deltaTime;       //Incremente the spread
          Fire();
      }else{
          spread.spread -= spread.decreasePerSecond * Time.deltaTime;      //Decrement the spread        
      }
      
      spread.spread = Mathf.Clamp(spread.spread, spread.minSpread, spread.maxSpread);  
  }
          
  function OnGUI (){
      var centerPoint = Vector2(Screen.width / 2, Screen.height / 2);
                 
      if(drawCrosshair){
          GUI.Box(Rect(centerPoint.x - width / 2, centerPoint.y - (height + spread.spread), width, height), "", lineStyle);
          GUI.Box(Rect(centerPoint.x - width / 2, centerPoint.y + spread.spread, width, height), "", lineStyle);
          GUI.Box(Rect(centerPoint.x + spread.spread, (centerPoint.y - width / 2), height , width), "", lineStyle);
          GUI.Box(Rect(centerPoint.x - (height + spread.spread), (centerPoint.y - width / 2), height , width), "", lineStyle);
      }   
  }
  
  function Fire(){
      //Carry out your normal shooting and stuff
  }
  
      //Applies color to the crosshair
  function SetColor(myTexture : Texture2D, myColor : Color){
      for (var y : int = 0; y < myTexture.height; ++y){
          for (var x : int = 0; x < myTexture.width; ++x){
              myTexture.SetPixel(x, y, myColor);
          }
      }
      
      myTexture.Apply();
  }