Just the complete truth is the best. Don't give them advice that will make them feel better, don't play w/ thier emotions. It may hurt, but the truth and telling them the right thing to do is always best in the long run. Thats what I do w/ my hosebeast EX. Gawd, just thinking about her gives me chills.
Heh, now that I'm reading all of these, this could be one of the best opinions, IMHO that is.