“But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican.” Jesus in Matthew 18:16-17 (KJV)
God has boundaries, so should you. He doesn’t let people walk all over Him. If they’re unrepentant, unremorseful, treat him like an unbeliever. Paraphrased from Leslie Varnick, Christian author, youtube videos.