I agree with the part about repeating it. For years and even to an extent now I have very low self esteem and it is hard at times to keep that negative stuff out...I actually write a song about it, kind of dark but it is basically about that voice in your head that wants to take you down.
Did you ever see that picture that has been passed around the internet over the years where there is a kitten in front f a mirror and he sees a lion? Yeah, that can work and it can be hard but you have to forget the opinion of this hurtful person and put up your mantle and annex you head back...trust me I know.
Best!