have your tried putting -windowed in the launch command?
I am also still having this problem even though there are patches that say they should have fixed it. I have tried launching the game with both the -fullscreen and -windowed launch commands and neither have worked. It even says its running fullscreen while not being able to keep my mouse within the game's screen if I move it across the border of my monitors. I'd expect this issue to have been fixed before release since it makes this completely unplayable with 2 monitors