What is self-righteous?

My friend and I had a little fight. We hadn’t talked for a few days since she was away and when she came back, she kept replying with 1 word and that was so not like her. I asked her if everything is okay and she said yeah. Then I told her she doesn’t seem sociable and then she replied “me? Not sociable?!” With a bunch of laughing smileys. Then I asked if I did something wrong and she said no, the next day we started talking normally and I told her about a guy (I’m a girl btw) and she told me to be careful about him and so on (she doesn’t know him) , but there was nothing to be careful about because I know him well and she replied with a short reply again saying “it’s your life, see ya” and then I told her that she’s making me feel like I did something wrong again and she replied with “maybe then,you did? Or you’re self-righteous to see it” What does that mean? :( I didn’t reply to her after that. Even though I don’t really get it, I got a little hurt. It’s not like her.