Unless you caught the growing tip by cutting into the leaves when you cut the flower stem, the damage you're seeing is much more likely to be from the severe winter. Check the trunk or stem of the plant for signs of rotting, with or without oozing of white stuff or orange gunk. If none, then just leave it (though you can remove any leaves that are dead). It may shoot new growth from the base or up the trunk, and when it does, cut back to that by sawing down the trunk to that point. You may have to wait till June to see any signs of growth. If you do have rotting areas, cut back beyond those now.