Selfish people or what ??
I hear you. There is a lot of selfishness in the world these days. Our current social media environment is really bringing out the worst in people IMO. But I tend to find that heavy gossipers are usually selfish narcs. They love spreading bad news about everyone as it makes them feel better about themselves. It sounds like you may be dealing with that.
You as an empath are a natural giver. You are probably always there for your friends and would give the shirt off your back to help them. Also as an empath you likely pick up on selfishness and detest it. That's why your friend’s behaviors are getting under your skin (it bothers you more than it does others).
Life is like the old saying that givers give, and takers take. The selfish (particularly narcs) are going to take, take, take in life. And when they are done taking everything out of you that they need, they will move on. You are already seeing that in your dynamics where your friend is ignoring your advice and moving on seeking others advice. Your friend already got good advice from you. But it's not the advice from others she is really seeking. She wants the attention and energy she gains by seeking out others advice and approval. In other words, she used you and moved on to get seek out more attention and feedback. It’s highly annoying and hurtful and is textbook narcissist behavior.
At some point those types of friends will either completely move on from you or you will do it yourself and cut them off. One of the best lessons I learned from another empath was to not let people use me and to be careful who I let into my life. And while implementing that advice I have cut narcs and really self-centered people out of my life. There is a lot less drama and much more happiness this way.