They pranked me, am i taking it a bit serious?

he just wanted to create a wedge in your friendship so that she can confide in him only. typical mind trick that guys play on girls to get the friends out of the picture. just distance your self for a bit when he hurts her she will be back trust me. and next time she comes with a sob story whether true or false. just tell her that" i understand your hurt but YOU have to decide whether or not the relationship is worth it. and whatever your decision is i will support you 100% because you are my friend. all i can do is listen and provide a shoulder because no matter what i say in the end your going to make your own decision. so im not going to influence you, i am going to show you support though" say that and i almost can guarantee you wont have this problem again. you always have to allow people to see things for themselves, because people these days have little trust value. they are quick to make the wrong assumptions about the people that there for them. and also next time dont play both sides of the field that answer i gave will leave you in neutral. good luck