How do I get rid of my empathy?

You fight your empathy.

Physically

Skyrim Final Boss ahh

What do you mean by "wronged me"? It will help me answer the questions you have.

Overcome ‘nice guy’ sydrome. Stop acting like a self-victimizing codependent.

Practice not only saying ‘no’ to requests from others, but also do so without feeling the need to provide any explanation or justify your answer.

’No’ is a complete statement in itself.

#5...that's what I was going to suggest...

Since you hold grudges, make a list of everyone else’s sins. Then have a long think over who it’s realistically possible to get revenge on, who you can only parry and who you should just stay away from. Try to figure what you actually have the ability to do. Take some baby steps. These people will never switch to your side or stop antagonising you. You’re going to blow and do something sooner or later, no matter how kind you are. Whether you get punished for doing it or not is up to you.