Tried to switch into 1st gear on the highway

Yeah, I know I'm an idiot and I would really appreciate no jokes or scolding as I know this was really dumb and I'm absolutely crushed and ashamed. A friend at work told me I'd mess up my manual car by switching into first on the highway. I've been driving manual 2001 Honda Civic for 5 years and thought how crazy it was that I've never accidentally switched into 1st gear at high speeds. I mean, its right there, very close to 4th and it would just take one movement of an inch or two with my hand, there's no way that would destroy the car right? The next day I was going 70mph on the highway and had an itching curiosity. I pushed in the clutch, switched to neutral. then tried to put it into 1st gear. Car wouldn't let me. it made a very quiet noise and just wouldn't move into gear. my clutch was fully pushed to the floor this whole time. I thought alright that answers the question. Switched back into 5th gear and tried to continue driving but could no longer accelerate. Pulled over to the side of the highway. Some backstory, a few years ago in my first week of driving the car I was going 55 and tried to switch into 5th gear for my first time but forgot where it was and tried to jam it into reverse instead, and heard an awful loud grinding sound. I just put it into 5th instead and it was completely fine, nothing happened. So I figured this wasn't even as bad as that since it didn't let me go into gear and it didn't even make that awful grinding noise. However here I was on the side of the highway, I tried to drive but it wouldn't move. Car engine was on, rpms would go up when I hit the gas. Clutch pedal felt completely normal, and I was able to switch into gear with no problem but the car would not move. Turned the engine off for a few minutes and then back on and same thing. Wouldn't drive in reverse, I even tried starting from 2nd gear but it still wouldn't move. Called a mechanic panicked who walked me through trouble shooting and instructed me to try to switch into gear while not touching the clutch. I did and it easily slid into gear without stalling out or any reaction from the car. The mechanic told me my clutch is shot and has to be replaced. I had it towed to a nearby shop and won't find out till Monday if thats true. I'm searching for any hope that that's not the case or any advice of what I should do. Thank you guys