Lets say your best friend all of a sudden starts to like ur ex. u might get upset, or angry .but really you have no controll . if you really have a problam with it tell ur best friend how you feel. just remeber that if they tell u they like ur ex. let it go. dont get mad at them . find someone eles . let them have there fun just ask him/her not to show PDA (public display of affection ) in frount of you . but lets say you are really upset just sit down and talk about it sooner or later you will relize its not such a big deal butyou still might be hurting inside and thats normal.just hand in there you'll find some one better !!!