How do I prevent my Facebook friends from knowing one of my Facebook friends?

[very old man]

A friend of my Ex wants to be my Facebook friend. If I accept him, everybody on my friend list will know and they may boycott him. So, is there a way to accept him as a friend on Facebook without letting the rest of the people on my friend list know about that? In other words, if I accept "A" as a friend, is there a way to prevent B, C, D, E, F, etc on my friend list know about the existence of "A" as my Facebook friend?

[takara]

Hide your friends list