I m playing as the French MTW 1.1 Early/Conquest/Normal.

First time I m playing. My latest king has two crowns and has just been excommunicated for zapping The English too many times. Im not too keen on him but I ve never assassinated a King before:

is it advisable?

what are the consequences?

what should I look out for before commiting myself to such a heinous Macbethian action?