Clutch / Gears / HELP!

Hey everyone!
I purchased an '04 Manual Outback from a friend a few months ago. Its
been driving fine, but then yesterday the oddest thing happened with the
clutch. I tried googling the answer but to no avail.

Over the course of a few minutes whilst driving, the clutch pedal started
depressing lower and lower toward the floor board. It got to the point where
I was physically having too push the clutch pedal 'INTO' the floorboard to
even be able to change gears.

With the clutch pedal completely pushed down with all my strength, I had to
use two hands to physically heave the shifter into 1st, then time the revs and
heave it into second. I literally had to run stop signs because I physically
couldn't get my car into first gear from neutral. When it was in first gear,
even with the clutch fully depressed (at a red light) the car was creeping
forward and gagging for gas.

I found mentions to something called a salve valve? potentially bleeding the
clutch? I'm a student, and work part time, so $ is very tight, my step father
has plenty of tools in his arsenal, but we just need a point in the right
direction!

Thank you so much in advance for taking the time to read this!