Returning a very heavy right sidespin serve

How can i return a very heavy right sidespin serve (im a left handed player)

Hi,

It is a matter of angling your racket away from where the ball wants to go with the spin.  So if the ball wants to go to the right then face your racket to the left.  This will counteract the spin.   Don't try to do too much with your action, just use the angle of the racket.