This happened to me when I was 18 with a '75 Caddy I had recently bought. Good news is my dad briefed me well one day on cruise control. He told
if it ever "sticks" and I can't disengage the cruise, put the car into nuetral, guide it to the side of the road and stop, slam it into part, shut off the engine. He showed me under the hood the thingy that attaches to the throttle, it looked like a tiny brake booster and attached to the throttle with a key chain looking thing. He said just break the chain. And that's what I did, was on 93 when it happened. Looked around for a large rock, broke the chain, started the car back up and drove it home. Had a dealer fix it. Dad saved my life that day.
That sounded pretty scary.