If you have children, you must maintain a relationship with your former spouse after a divorce. This is easier said than done when your ex consistently exhibits "toxic" behaviors, which can harm you, your mental health, and your relationship with your children. While you can't change a person's actions, you can control how you choose to respond to them. The Good Men Project offers the following advice to help you along.
While it can be difficult, try your best to remain neutral. When your ex exhibits insulting behavior or attempts to goad you into a fight, refrain from responding. If you see this behavior is having an impact on your children, engage them in conversation about the matter but stop short of laying blame on your ex or criticizing her. If your children are having a hard time sorting out their feelings, consider seeking professional counseling. This will provide a safe place for them to air their emotions without reprisal from an angry ex.
If you believe you're the victim of parental alienation, you may need to consult with your divorce attorney. Parental alienation is the tactic of turning kids against the other parent to gain an advantage. In many cases, custody orders have clauses related to parental alienation, meaning if your ex continually badmouths you to your kids and it's affecting your relationship, it could be a matter for the court to decide.
Finally, accept that nothing you say or do may be capable of changing your former spouse's behavior. In this case, all you can do is be the best parent possible and work to mitigate any stress that befalls your kids. Good parents get divorced all the time, but they accept that the best tactic is to keep children far away from any strife. While it's certainly frustrating when your ex behaves badly, you can't let it get in the way of your parenting.