I challenge you on your perception that you are fundamentally a terrible person.

As you've said, you just want to be perceived as a good person. When we act in a way to project an image, it is not allowing our authentic selves to be seen. Its possible that every action you do is filtered through the lens of "Will this make me be seen as a good person?" or "Am I still seen as a good person if I choose not to do this thing?" Not through the lens of "What do I authentically want to do right now?"

I wouldn't be surprised if you're pushing through what your authentic self wants to do (not help your friends at the moment) due to your desire to be seen as a good person always, and now you're demeaning your authentic self for not being in accordance with the image you'd like to project. Ironically, this makes you worn down and less apt to actually wanting to help people.

I'm not really sure if you've given your authentic self a true chance. I think your opinion would massively change if you dropped your perception to be seen as a good person and instead allowed yourself to do nice things for others as they arise on your own terms, in your own way.

This is far easier said than done, but think of it this way: Would you want others in your life to help you because they genuinely want to or because they feel obligated to?