You have experienced a Hematoma (bruise) to the big toenail. Trimming it back will help, but if the entire nail is effected, the nail will eventually fall off and be replaced with a new one. Most people who participate in aggressive type sports experience hematoma to the toe nails. It is not normally a problem, but in your case, you went skiing with a new pair of boots that were not broken in; hence the hematoma. Give it time to completely heal before attemoting to ski in an agressive manner again. Give the boots time to break into your feet!
Keep the area clean and dry at all times, and clip off any part of nail that loosens up and lifts from the nail bed. Bandage the toe with gauze and a 'breathable' tape to protect the nail bed until a new nail emerges. You are right to use the peroxide to clean the wound, but only do so until it does not 'bubble' when applied. After that, use an antibiotic ointment under the bandage. Only bandage the toe for a couple of weeks, and only when wearing shoes; otherwise, leave it open to the air.