Sounds like maybe your clutch was slowly engaging as you held the pedal down. That's basically the same as when your brake pedal slowly sinks to the floor at a red light. You probably need a new clutch master cylinder.

Gonna DIY? Here's what you can check (without the engine running)...
The clutch slave cylinder is on the front of the tranny, kinda low & near the radiator fan motor. This small hydraulic cylinder pushes against a throw-out lever that sticks out from a hole in the tranny. Maybe it's covered up with a rubber boot.
It should push that lever about 12 or 13 mm when you press the clutch pedal down. Have someone push the pedal while you watch. Pump the clutch pedal up & down a few times, then hold it down on the floor. Keep holding it for a couple minutes. The lever is NOT supposed to slide back towards the slave cylinder. If it does, then you need a new master like I said above.