Defriend on Facebook With Caution

In a recent story from the Daily Mail, a woman became so angered over a Facebook spat she tried to burn down her former friends house.  This leads to the question, how do you decide who to friend or defriend on Facebook?

Is Facebook even worth the drama?  Based on calls that came into the show the past couple days, it seems like Facebook causes plenty of fights between friends and family. 

If you decide to defriend someone, how do you do it without it becoming a bigger issue? Like say, your former friend trying to burn down your house.