Hey man rest easy. The split isn’t that bad. You’ll be fine. You tied it up and propped it which is great. The only thing I’d add is some duct tape around the break. Trim off the leaves and growth sites at the part and wrap it with tape to strengthen the hold. The stalk will repair itself and probably even form a knuckle. As for moving it into the dark I wouldn’t do that. Plants are really resilient especially their veg phase. It’ll actually be more beneficial to have the regular 18 hours of light and 6 hours of dark man. If you check my diary I broke some stems, much worse than that, and I had one top doe off completely but the side growth became the new top. The other plants recovered and continued to grow just fine. The whole time they stayed in the tent to avoid further environmental stress and influence. Happy growing man