Cutting someone out of your life

I have a few people in my life where they know they are on the 'do not contact me list'... And some don't.. So far I've been lucky that those who don't know, I don't bump into them. My friend is in the situation you are in.. Well was in(since you already gave your number :p), as in he hasn't given the person his new number...However his situation puts me in a spot a lot of times, as I bump into this person quite often and a few times the person has asked for my friends new number(but I quickly change the conversation, pretending I didn't hear the question)... Whether or not to tell them is kinda tricky... Sometimes when you tell them it might actually make things worse, sometimes not telling them it'll make things worse. For own experience so far, things seems to be working, although I know hiding behind a bush really isn't a long term idea that's gonna hold water. Maybe a new year resolution would be to tell them... Wonder what they'll say...