What do you do when your best friend ex'x likes and you asked you at?

If you are interested in this "ex" then talking to your bestfriend explain that this person has asked you out and you were wondering if that would bother them - if it does and you respect your friend then you decline, if your friend is ok with it then do what you prefer but it should be respected that you asked if it was ok before just going ahead with this. If you do not want anything to do with this person simply say no your not interested. Remember though your friend is not with him for a reason and ask yourself if your willing to be with him knowing everything you may.