I don't want to sound rude or anything so don't take this the wrong way, but I see you talking about how you want to make smaller updates after chapter 1. but why not cut this giant update in smaller segments and release them a little whenever, keeping your community entertained while releasing a little of the pressure.
now I don't know anything about coding for example so I don't even know if this would be easier or even possible to do, but it was just a thought. anyway good luck with the update and everything else you have going in life and don't overwork yourself!