Most likely just need a new gasket. The gasket I am guessing is where you see the number 1 & 3 in the diagram.
RealOEM.com BMW E53 X5 4.4i Exhaust manifold
If its leaking from gaskets 4 or 5 then that would be quite a bit more work involved.
Not sure what you asking about the head being broken? An exhaust leak should not cause a head to be damaged in any way.