Mistress seduced my husband. How can we get rid of this evil?

As long as you try to pull your husband's heart back and let him abandon her, this is the best revenge. It is illegal to find someone to beat her. If you don't want a divorce, you'd better focus on your husband, ignore your mistress, try to control their communication and break off the relationship. If you make a mountain out of a molehill, it's not good for you.