Sefer Ha’mitzvos Ha’Katzar (The concise book of mitzvos) By the Chofetz Chaim
This book lists the Torah mitzvos that can be observed today
Second Section – the Negative Commandments
78. It is a negative commandment “do not hate another Jew who behaves properly”
As it states in Vayikra (Leviticus) 19:17, “do not hate your brother in your heart.” When one Jew sins against another one, a person should not keep hatred inside his heart and remain silent. Rather, it is a commandment to make known to him the wrong he did and say to him, “why did you do such and such a thing?” A person should erase the hatred from his heart. But if he sees him committing a sin and warned him, but the other person did not repent [he continues sinning], then it is a commandment to hate him (because he does not act as your brother.)
This applies in all places and at all times, for men and for women.
4. Be kind to yourself. Speaking badly even about yourself is unethical.
הלכות שמירת הלשון 