The father of the American contractor who was beheaded last month in Iraq, blasted the Bush administration yesterday in London. Michael Berg, whose son Nicholas was killed, said “People like George Bush and Donald Rumsfeld don’t see the pain that people have to bear — they don’t know what it feels like to have your guts ripped out. What I’m trying to do is show to the American people and the British people … that war has a wretchedly horrible face.”