Thanks for all your responses, they are all appreciated.

My male friend is a very good friend who I've known for 20 years before I ever knew my boyfriend. I see no problem with meeting him and going out. My boyfriend does not know him so is unsure of his incentives but I know that nothing will happen and should it happen my friend will not go any further when I explain i am already with someone. He will respect my wishes as he is a good friend. I have explained this to my boyfriend but he is unsure and I dont blame him either as he does not know him, but that doesnt give him an excuse to punch me. Dealing with it by talking further would have been the ideal ie "i dont want you going out with your friend because ...." i would have worked something out.