FTP to your site and rename the plugin folder to wordfence.old and see if that lets you back in. That will deactivate the plugin. If your login works again, try renaming back to wordfence and try again. Hopefully it's a temporary glitch.
If it's still messed up, I'd delete the plugin folder, restore your .htaccess (again), then connect to the database and delete all the wf tables. Then reinstall Wordfence.