Rabbi Pliskin in Love Your Neighbor p. 275

Lo tisneh es achicha bilvovecha (Leviticus 19.17)

Do not hate your brother in your heart...

The Talmud says (Erchin 16a) and Sifra that this verse refers to concealing hatred. That is the most dangerous. If someone explicitly tells a person that he hates him, although he does not violate this prohibition, he does however violate the commandment "Love your fellow Man"

The Torah refers to hate in the context of a "brother". This implies that no less than the type of love one has for a brother is appropriate for one's fellow Jew, and less than that constitutes hatred (Ohr Hachaim).

Orchos Tzadikim says different types of hatred and different solutions:

1. Wronging you in financial matters.

2. Jealousy

3. His not doing you favors.

4. Professional competition.

5. Causeless.

6. He tried to correct you.

7. He tries to do good and pursue righteousness.

The corresponding solutions:

1. Seek out the person, ask for an explanation of his behavior.

2. Force yourself to uproot your feeling of jealousy by awareness that G-d bestows to each according to His Will.

3. Trust G-d. Everything G-d does is for the best.

4. Strengthen your realization that no one can exceed their earning power that G-d has set for them.

5. Be aware that causeless hatred is a serious offense.

6. You should be grateful to the person for the admonishment.

7. Know that this is the same as hating G-d.