I’ve been netting my plant in veg for three week...

Bem amigo isso está sempre acontecer comigo, eu deixo rebento parto pir algumas horas, se na murcha fica, mas se murcha como o seu eu retiro, (faso clone). Bem possível rebento colar, mas se colar já perdeu altura com rebento concorrentes, ficará sempre para trás, e sua planta está em baixo stress na tentativa de recuprear seu rebento. Não veja isso como uma perda, mas sim uma mais valia para restantes rebentos.

I'm afraid that's gone. If it wilts like that, the damage is too severe. If it was going to be able to recover, it would stay upright. Even for a clone, you're probably too late, but worth a try. Sorry for your loss

Owie! Tapeable, or no???

tape it back together and hopefully within 36-48 hours it shows signs of life. Should see an improvement in first 24hrs even if the wilting doesn't completely abate. it'll be obvious if it cotinues to die. the plant will make the choice for you, no worries.

Well you could make sure to not risk molt or other infectionstuff by removing it gentle. cut over the last node unter the crack and accept a topping. You get 2 new strong headdies :)

It might recover it might not, If it stays dead and dries out just cut the branch off, the plant will adapt. If its looking like it might survive you can help it maintain moisture by wrapping a plastic bag aorund the site of injury. branch and all. They can sometimes encourage mold growth though so proceed at your own risk. Clones are often in a high RH environment with no issues but left long enough and it will get gross.