Answered by Sayyidi al-Ḥabīb `Umar bin Hafīẓ (may Allāh preserve him and benefit us by him).
How do we deal with Muslims who mistreat us?
By treating them well and praying for them. Allah says: A good deed and a bad deed are not equal. Repel [evil] with that which is better. The outcome of this is: then the one whom between him and you was enmity will become as if he is an intimate friend. (Fuṣṣilat, 41:34)