Selfish is an adjective used to express disapproval of someones self serving behaviour. A selfish person cares only about their own situation, they don't care about other people. Selfish = caring only about what you want or need without any thought for the needs or wishes of other people Proud has a few different meanings. Proud adjective (SATISFIED): feeling pleasure and satisfaction because you or people connected with you have done or got something good. Proud adjective (RESPECTING YOURSELF) having or showing respect for yourself. Proud adjective (FEELING IMPORTANT) feeling that you are better and more important than other people. The first two definitions are used in a positive way. For example: I felt really proud when I graduated from university. (satisfied). We may be poor but we are a proud people. (Respecting yourself). Whereas the last definition is disapproving. For example: He is too proud to admit when he is in the wrong. (feeling important). https://dictionary.cambridge.org/dictionary/english/proud

I'm to a native speaker so take what I say with a grain of salt, but to be proud means to feel satisfied because of someone of something. Let's say you have just found a cure for cancer, in that case you fried could say "I'm proud of you!". The word "selfish' has a negative connotation to it, it means to act in a way which benefits you, so you only do what’s best for you and disregard others. I hope I’ve helped you a little bit