Okay, deleting the mods folder and reinstalling forge seemed to do the trick. Without any mods, it ran fine. However, as soon as I dragged the latest version of Optifine into the mods folder, when I tried to launch the forge version, it again, came up black.
crash report:
https://pastebin.com/LkArCJph
fml-client-latest.log:
https://pastebin.com/kJu0mVg5