@AmbcrLies You can force-quit TS4, or any application that's not responding, with cmd-optn-esc. A window will appear, and you can select which application(s) to close.
This particular save has to be corrupt. If it didn't have a problem before, it certainly does now, so if you want to keep playing it, your only option is to go back to a previous version. Even if you never use "save as," you should be able to pick from several earlier save points.
https://help.ea.com/en-us/help/the-sims/the-sims-4/how-to-restore-a-previous-saved-game-in-the-sims-4/