You seem to be confusing force with momemtum. Newton's 3rd law states:
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body
But force is mass * acceleration. So the force exerted against Wolverine's body will be due to the acceleration (or deceleration) of the object that he is cutting.
So let's take a look at an example. In this video at 1:55 Wolverine cuts through an army vehicle while riding his motorbike.
Because Wolverine's claws are so sharp (due to Adamantium being the strongest material known to man) the army vehicle doesn't actually slow down (very much) so little force is actually exerted on Wolverine, hence why he isn't thrown backwards. In fact, the vehicle barely moves until Wolverine hits the tyre.