Where does my memory go?

I am on macbook white unibody 2009, earlier version, not the second one.

i was freeing up some space on my mac, and i had 100 gb free, the next thing i see it's 79bg free. where the **** does my memory go? i delete files to leave nothing and everything is taking up. it actually increased by 26 gb after i removed windows partition of 10gb with bootcamp. what is wrong with it, jesus christ. it should free space, not take up more memory.

library is 12.77gb

system is 10.38gb

applications 21.95

users 71.5

238.93-116.6=122.33gb, this is how much i should have, and it shows that i have 77.01 GB available. what the **** is happening?