I am not going to give money to a person who probably really needs it.
Why? do you think this person doesn't deserve your help?
Although I'm capable of helping him, he offended me a lot in the past.
Your anger about him is totally justifiable but you should still help him if he's in need. It's always good to help people.
I don't care anymore. I'm too mad at him.
If he is in need of help then you ought to help him. Even though you may have bad feelings about him, it would probably make you feel better to help ultimately.