Narcissistic Parents Accuse Fiancé of Abuse

I need help! My narcissistic parents believe my fiancé is abusive all because I don’t want to hang out with my family anymore. A little background: my parents emotionally abused me since I was in middle school and refuse to believe me when I brought it up to them. I had since cut them out of my life to better improve my mental health but in doing so they banned me from seeing my younger siblings who are not adults yet. So they can’t make their own decision to come see me. The only way I thought I could see my siblings would be to start talking to my parents again. But it feels miserable. My parents still don’t call me my name and use my deadname instead. And I imagine they won’t abide by most or all of the other boundaries I set. Im supposed to have dinner with them in a couple days but I really don’t want to. They don’t make me feel comfortable or emotionally safe. They’re manipulative and I can’t be myself around them without judgement and backlash. I want to cancel dinner but I’m so afraid that if I do, they’ll think my fiancé is abusing me and forcing me away from my family. I fear they may call the police or someone to do an investigation on us. I don’t know if they would actually do that or not but I’m afraid of the chance. I don’t my fiancés life to be in shambles because of being accused of abuse. Even false accusations can ruin someone’s life. And I don’t want that for my love. Basically I just want to know if I should suck it up and go to dinner or if there is a way to not go and avoid the storm I’m so afraid is brewing? I just don’t know how to fix this.