Also press on the top of the knife instead of only using the handle. And cut it on an angle so it's not trying to press down on the whole length at once. And don't try to pull the blade towards the handle (which is usually the ideal way to cut) if you're cutting that much cheese because it grips the entire length of the blade and that might have more force than the handle can handle (heh), like in this case.
Lubricating the blade could help, maybe use a nice chili oil to give the edge a bit of a kick.
A long time ago my grandfather had a cheeseboard that had a small cut into it. And a metal bar that went around the outside with a wire that you would pull down to cut through the cheese. It was easier to use than knives and was fairly easy to clean. Similar to this: