"Cogito, ergo sum" which translates to "I think therefore I am" is the first principle of a philosophy defined by René Descartes that we could expand to "I think therefore I am right" or "I think therefore I am good". How, or what, we think feels right to us as why else would we be thinking about it? It's easy for us to internally feel like a victim of a situation and justified in our overreactions of it.
To "be" a good person is to "do" good things not simply thinking good thoughts and it's for other people to judge what our good deeds are; It's for other people to determine how good we are.
The picture we have of ourselves and how other perceives us are two separate entities and self improvement requires considerations of both. Become the best version of yourself by paying attention to the constructive criticism people are saying about you.