flyugyeom The launcher crashing is a known issue:
Launcher crashes when I open the downloads tab in Sims 3 | EA Forums - 12167613
For the inability to login at the Main Menu, open Keychain Access, in Applications, Utilities, search for sims3 , and delete any entries you find. This should reset the login process.
For the rest, try renaming or removing the Sims 3 folder in Documents > Electronic Arts. This will prevent your saves and other user content from loading, but the files will be intact and can be restored later. In the interim, don't add anything to the new folder; just start a new save and see how it runs. If you want to change any graphics settings other than the resolution, do so at the Main Menu and quit to desktop before loading a save.
Test in Sunset Valley and let me know how the game runs. If you get another crash, try again but with your computer offline. You can sign into the EA App and put it in offline mode, then disable wifi before opening the launcher.