So, with the release of AE, many of our games got screwed, despite mods and expansion keeping this game replayable, they didn't care to make the update optional or anything, it was somewhat just sprung on us, but it's okay, I have the solution!

All this guide contains is a small set of steps, easy to follow, and a download link to a file on Nexus Mods that will basically reverse the patch. I was able to run it, and the first two gamesaves I tried were corrupt because of the update, they were autosaves that it created during me trying to get things to work, but the third one worked and I was able to re-save to avoid it happening again, but here are the steps to take first:

1. Go to your Library on Steam
2. Right-click Skyrim: Special Edition and select Properties
3. Select the Update tab
4. Set the game to ONLY update when run via Steam
(Running by the SKSE loader or Mod Manager won't trigger this update)

Then, once that's done, go to this link here:
https://www.nexusmods.com/skyrimspecialedition/mods/57618?tab=description

Download, extract both the .exe and the folder into a single folder, and run the .exe, select patch, and let it do what it does. If you've updated SKSE, UN-update it, simply grab the old SE version from their site (Literally google SKSE and you'll find it, if you're into modding I imagine you already know how this works) and reinstall it over top of the new preliminary AE version, all your old mods that were SKSE-dependent will now work again!

It has almost 7k downloads, but I imagine it'll spread as more people find out about it, huge thanks to Halgari as the creator of the tool I've linked you to, what an absolute legend.