I don't know why, but I was very selfish and violent.
Does your selfish and violent behavior make you feel regretful?
I'm not that bad any more.
I am glad you think you are improving. It is bad to behave in a violent or selfish manner. If you feel this way a lot you should seek help.
Pretty sure you are the one that needs to change.
I'd recommend listening to what I have to say. Having these feelings isn't good for maintaining good mental health. I do think talking to someone would be beneficial for you.