Soft-Bricked Samsung Galaxy S5 - "Set Warranty Bit: Kernel"
Samsung phones require a special version of Xposed -  the regular one just won't work as you experienced.

Since you can still get into TWRP, the situation is still under control. Uninstall the current one with the uninstaller from the official Xposed thread, try booting up, and if it returns to normal, download and install the special version.