Let's be honest...Toxic 3rd parties...the uninvited guests.
Ever feel like you don't want to rock the boat in a relationship by telling the TRUTH? I know, I've been there. You have an in-law or a friend that is connected to your relationship, and they are really toxic. But no one wants to address the elephant in the room--THEIR TOXICITY--because it would be too painful, it would create disruption and conflict, and it may come off as rude and disrespectful. Everyone appeases them, enabling them, and thinks that's doing that person a favor.
Meanwhile, the toxic behavior of this third party exerting influence on your relationship just keeps eating at you. And you're fuming...on the inside. I'm here to tell you that you are only hurting yourself by keeping that molten lava inside of the volcano of your soul. Someone needs to say something, and that someone is YOU. With respect, you have to address this person head-on.
Here are some tips:
1) Timing is Everything. Speak to someone in a time where you're not in the middle of a heated argument. Laid-back environments are best, preferably not in someone's home.
2) Live with the Consequences. There may be fallout. Heck, there very likely WILL be fallout. Have you hit the point of no return? The point when you recognize that for the sake of your health, you've got to share with this person how they make you feel? It's okay to create healthy boundaries.
3) Talk About How You Feel. Someone can be angry with you and refuse to take ownership, but no one can say you don't have a right to feel the way you do. Practice: "I feel _____ (disappointed, betrayed, unloved, etc.) when you speak poorly of my _____ (performance, writing, cooking, clothing choices, etc.) in front of others." Good, just plug in what makes sense.
4) Recruit an Ally. You aren't the only one who has been hurt by this person. Oftentimes, an ally can help you better understand what makes this person feel entitled to their toxicity. If your ally is your spouse, that's the best scenario. Regardless, you should consult with them before you make your move. Your ally should be someone that you know can call you out as well when you're in the wrong!!
5) Get Your Thoughts in Order. Don't just appear to be willy nilly listing off grievances. Have a set idea of what you will be addressing and boundaries you will be implementing. There should always be a results-based approach, even if those results never materialize.
Sometimes we think that people will just fade away in the background, and perhaps we won't need to address their issues in a head to head confrontation. But, often, toxic 3rd parties who are powerful will just continue to stick around. I'm a firm believer that people will treat you the way you let them treat you. Will you cause conflict? Maybe. But asserting your position considerately is part and parcel of respecting yourself.