Connect to Mac Mini without sharing the screen
Using other software, RealVNC, should fix your problem.


Download RealVNC. You only need a personal license, which is free.
Enable Remote Management. Go into System Preferences > Sharing > Remote Management.
Configure RealVNC. It can be set up pretty much however you'd like.
Connect to your computer. This will land you on the login page for your mac, and will only share a screen with it if logged in as the current user.