A very senior person at work has messed up and instead of taking responsibility he has instructed me to do something which is unethical and probably illegal. He is partly blaming me for what has occurred due to the fact that I didn't challenge him before he did it, this was not possible as I didn't know about it, he says I did. I have told him what needs to be done, he refuses and has sent me an intimidating email basically saying it's my job to sort it. He is a highly political person, ruthless, and has already caused 2 people to leave citing bullying by him, costing a lot of money for the company. He has suffered no consequences for this. I am so stressed and upset by it all, I feel physically ill. I am out of my depth and don't know how to deal with him.