Leave your coworker out of it. Once they know that you know his salary, any advantage you have will be lost. Do your research, and figure out what a fair price is for your job in your city. If it’s higher than what you are being paid, it’s not out of line to go to your boss with that data to insist on a raise. However, if you go off half cooked and upset because your coworker makes more than you, you’ll only wind up looking like an ass. Adults create reasoned arguments based on facts. Children whine and complain over a perceived unfairness.

I would date a person who suffered a severe mental illness in the past if I like them, they like me, we are compatible, and we are both able to be understanding and accepting of each other’s strengths and weaknesses. People who have suffered severe mental illness are not in some way inherently different from other people. If they still have mental illness and that is not something you can or are willing to live with, you probably shouldn’t date them. If they only had it in the past but no longer, but you judge them for having it in the past, you probably shouldn’t date them. If you are willing to accept them for who they are, whether or not they have mental illness now, then you should date them.