Playing mage in pk can be very stressfull, especially if you are having bad luck. There will always be whiners who don't realise you just saved someone else and you couldn't tp them at the same time. So in their opinion you suck. Most people don't care whether you kept the party alive, they care about how much np they made. The mage sometimes also gets blamed before the healer eventhough the healer may have messed up or not but i guess that's what backup is for.
As said above if you can't take all that shiat pick another class.