Over 25 gb of space disappeared

Here's my problem: over the past couple days I did a really good clean out of my computer and managed to free up several gigabytes of data and was hovering around 233+ gb of free space.

Then in the last couple of days I noticed my trash file was taking a really long time to empty (I don't know if this is part of the problem but wanted to mention it just in case).

Last night I noticed I was missing quite a lot of space on my drive, it was around 205 gigs now. I discovered I had accidentally set some large torrent files to be on my main drive instead of an external. No matter, I figured! I would just delete them and start them over on the external. But my disk space didn't seem to change. So I rebooted - after all I had recently used Photoshop and that tends to hog a bunch of space and I don't get it back until I reboot.

I rebooted and there was still the same ~205 gb of free space. I was very confused. I was even more confused when I checked "About My Mac" and saw that it was telling me that in actual fact I only had around 90gbs of free space. THE HECK!?

I did notice that my "backups" were surprisingly high - 119gb in fact. This was especially curious since I have a time machine drive (time capsule) thats supposed to be backing up hourly. I did get a message this morning telling me it was full, but isn't it supposed to clear itself out?

Running WhatSize (it's still running by the way) I see that my .MobileBackups folder is a gargantuan 134gb! I thought these were temporary! For when I'm not connected to Time Machine (WHICH I AM!)

What in the **** is going on? How did I magically lose close to 25 gigs? And how the **** do I get it back?