You can be compassionate without becoming available for repeated disrespect.

Compassion is an understanding of why someone behaves as they do. It does not require you to keep receiving the behavior. Those two get fused because refusing access feels unkind, and so people stay in situations that damage them out of an idea about what caring requires.

Hold both at once: they may have real reasons, and you may still need to step back. You can say so plainly without accusation. Understanding someone is not the same as absorbing what they do.