@ami888 Try using this tool instead, in fullscreen mode:
https://community.pcgamingwiki.com/files/file/84-d3doverrider/?changelog=32
It's built on RivaTuner Statistics Server, but what it does is force vertical sync, which should help with the flickering.
If you get another crash, please move your entire Sims 3 folder out of Documents\Electronic Arts and onto your desktop. When you launch the game, a clean folder will spawn with no content. Don't add anything to it yet; just start a new save in Sunset Valley and let me know whether the game still crashes.
If you still get a crash in a clean folder, please post a new dxdiag. If you don't get a crash in the clean folder (but you did get a crash in the old folder), the issue is some content in the old folder or possibly the world you were playing in, so let me know what world was and we can go from there.