Is this fixable (major mistake while lst)

I e done the same many times . K bind tightly together with a combination of cling film and duct tape. Dunno if it "fixes" the wound but the plants always survived. Hope this helps good luck and chin up .

Intenta usar algun medio transpirable para unirla. Tal vez conta de teflon de fontanero, bridas o cables. Sera mejor que cinta adhesiva ya que prevendrá hongos y posible presentacion de raices en el tallo por falta de luz y humedad 🍀🍀

Just leave it, she will heal herself and continue growing as though nothing happened. Cannabis is an amazing plant!

Push it together I like to use little zip ties instead of tape so no moisture is trapped behind tape. Tape is not breathable.

Yes you could try to fix it by taping both sides together. Friend of mine use cable ties but not the best option as they might damage the stem. Garden tape would be a better option. The faster you do it the more chance you have to fix her. Good luck buddy!

push it together and tape it up... it may takea while to heal and the plant will be droopy. That's pretty major, though... all you can do is try. sooner you do it the more likely it heals of course...pinch it together and wrap some tape around it or something to hold it together fairly tightly -- without any more damage to vascular tissue. even if still droppy 2nd day. give it a second... i just broke a branch and it was 3 days before the terminal spruced back up. looked quite bad before that point. once it;s fully recovered, get the bandage/tape off so it doesn't restrict growth.... waiting a few extra days to be safe is no problem. It'll be stronger than before if it heals.