@unzx I don't play GTAO and so the prospect of playing it offline is not relevant for me.
You can either remove the mod and do a verify integrity, or you can try to contact the mod creator and ask for a fix.
If you disabled dinput8.dll and did a verify integrity there isn't any reason for your game not to run, unless you have other issues (Hardware, Windows).
Although I never recommend it, worst case, do a complete reinstall - but as I wrote above a verify integrity should work.
A verify integrity, or a reinstall, however will not fix a corrupt save game file as these are not overwritten. So you may want to backup your save games and then delete them and then restart GTA5 fresh. This has happened to me once and ironically the error message never was about corrupt data.
In passing, I've never heard of this mod and frankly it sounds like a true crock of shit.