Is it normal to have an obsession with getting even when someone stabs you in the back?

It isn't normal: We all want justice in this world, but it isn't always available or even appropriate most of the time. There are a lot of sayings and warnings about revenge most of which imply revenge is not a good thing. If you are not able to let go of your anger i would be inclined to encourage you to get counseling to find out why you are so angry and develop a better solution than revenge.

Many people. Choose : To do that , others can choose to forget and forgive , and i hope u can be from this type.

Obsession: it is a natural response of the human mind to think the way you are. Leave it to the legal system to figure out the punishment you should not be the one acting out. Talk to your counselor or Psychiatrist sometimes talking it over will help ease your mind