Am I a surgeon or did I fuck it up

Try to leave a bit more stem above the remaining top node. It helps avoid any splitting if you train it later on. This won't eliminate the possibility but reduces risk and can reduce the amount of damage cuased if it does split. Just has one plant split apart but was only partial because of the extra stem left behind. A little tape to hold it tight and didn't even get any wilt from the partially damaged vascular tissue. Without it, the entire node would have split more severely, and I would have had greater probabilty of losing both of the branches. If these will simply grow vertically with no training, it is not an issue at all and perfectly fine as you did it. The only concern is if there is some sort of force applied to spread them apart - LST, scrog, whatever.. "training" in general. Be very caerful if applying any force to these top 2 resulting branches. Shape each stem first before tying it down or forcing under a trellis/scrog, so it causes less stress on the "fork" in stem.