How to delete an ion-list item using an ActionSheet?

I need to delete and item from a list (that is populated from an array) using and ActionSheet (trigger by an on-hold event) instead of the standard ng-click.

The problem is that I can't figure out how to pass the index numbre or the item id to locate it and delete it.

Here is the HTML:

<ion-list>
  <ion-item ng-repeat="mensaje in mensajes" class="item" ng-click="abrirMensaje()" 
  on-hold="mostrarMenu(mensaje)">
    <h2>{{ mensaje.alert }}</h2>
    <p>{{ mensaje.hid }}</p>
  </ion-item>
</ion-list>

And here is the controller for the ActionSheet:

$scope.mostrarMenu = function(mensaje) {

    // Show the action sheet
    var hideSheet = $ionicActionSheet.show({
        buttons: [
            { text: '<b>Compartir</b>' },
        ],
        destructiveText: '<b>Eliminar</b>',
        cancelText: '<b>Cancelar</b>',
        cancel: function() {
    },
        buttonClicked: function(index) {
        return true;
        },
        destructiveButtonClicked: function(mensaje) {
            return true;
        }
    });
};

Any ideas?