Aye, You have resurfaced a memory from 2019, my left gastroc popped while I was embarking on a run and I literally couldn't make it home, I had to call a friend who angrily came and picked me up. I couldn't walk for weeks. Even a month or two later I remember things felt like they were pretty back to normal and I carelessly jumped out of the car and reinjured my calf upon impact with the ground. Those were a rough few months. grateful I'm 100% healed now that's a distant memory.

RICE Rest, Ice, Compression, Elevation,

Oh I always forget the difference between a strain and a sprain and you say your hamstring is torn so I don't know yeah look forward to seeing your doctor.

Not medical advice, but maybe see about deferring your registration to next year (or depending on the race organizer, maybe even another race this year). I know it sucks but take care of yourself first.