The pimple on my vagina popped by itself and pus came out then blood. I'm really scared what should I do? I don't want to go to the doctor

Watch for recurrence. Soak in warm water and if it is better then just watch but if it returns you should see your doctor. You probably had an abscess but the differential is wide so with out a picture and full exam you should be careful. Also look up bartholin gland cysts.
Pimple. Now that's its popped it will probably heal quickly. If it doesn't heal within a week i would see your doctor.