Birthday cake

For my father-in-law's birthday, he wanted cheesecake.  I don't have a spring form pan so I used a ready graham crust.  I thought it came out nicely until my mother-in-law cut it and it was a total mess.  She blamed the knife not being sharp enough, but also I think you're supposed to use a warm knife or one dipped in water?  Everyone said it tasted good but maybe that was because once served, I topped it with cherries.