Sims 4 crashes repeatedly

I appreciate your suggestions so much as I had not tried these. Here's what all I did based on your suggestions (all reboots are clean boots).

From my main account:

The first thing I tried was setting the FPS to 60 and set to windowed. I left it this way for the majority of my testing but it had no impact.

The only peripheral I have is a mouse so unplugged and rebooted. Sims appeared to work great after this! Rebooted a few times and launched the game a few times. I was leaving the game on the main menu and not creating a new game since it tends to crash within the first few minutes of launch. I plugged back in my normal mouse, launched the game, crash on the menu. Unplugged it, reboot, launched the game, seemed stable, tried a different mouse, also stable. Since that seemed stable, created a new sim family and played for a long while (over 2 hours!). Had a little cry that it was finally working after all these months and it was just the stupid effing mouse and then CRASH. Once this happened, every subsequent attempt to load into a game, new or the one I had just created, failed with or without a mouse plugged in. ¯\_(ツ)_/¯  This isn't the first time this has happened either. I will make some sort of random change, do the reboot, and it will let me play to the point where I think I've finally fixed it, and then suddenly crash. 

Perfmon's definitely going back in my troubleshooting notebook, that was pretty helpful! I ran it and iGoSWServer was not crashing at the same time as Sims, but I still uninstalled the corresponding add-on software and disabled the driver anyway cos why not at this point. It did not make any impact on gameplay. I don't see anything else crashing at the same time Sims crashes.

As local admin:

Created the local admin account and tried. This was somehow worse. It wouldn't even load into the game menu at all even with clean boot and antivirus off. Normally it will at least load into the game menu after a few tries but not on this account.

Back to main account:

I decided at this point to uninstall again and install ONLY the base game. This worked great. Clean boot, antivirus on, original mouse plugged in, fresh install with just the base game and it ran fine, played for roughly an hour. When I exited the game, the EA app had downloaded and installed ALL of the game packs and add-ons I own. I double checked the settings and everything available to configure in the EA app was disabled so I have no idea why the EA app downloaded them anyway. Uninstalled again, cleaned directories, switched to local admin.

Back to local admin:

Deleted Electronics Arts folder from this user's Documents. Verified I didn't see any other EA/Electronics Arts stuff other than EA Desktop app. Reboot. Downloaded only base game, tried to launch, video card error (because it isn't in the GraphicsCards.sgr) then it crashed (it does not crash here on main account) and from then on I can't even launch the game at all. Restart EA app and then, despite having automatic downloads and everything else disabled in EA app settings, it STILL automatically starts to download every single pack I own and I have to cancel every individual one to get it to stop. I don't see anywhere that will let me bulk cancel everything in the download queue which is frustrating. Once it starts downloading these add-ons, it won't let me launch the game again until those packs are installed or I've cancelled all the pending downloads.

I tried to launch the game after I got them all cancelled and it let me into the game menu and all the way into a new game. Minimized so I could see the EA app and of course, there it goes downloading every single add on yet again....

Is there any way to force this to stop somewhere besides in the EA app settings? Am I somehow missing a setting to disable?? Is this even worthwhile trying?