Inviting my family could lead to me being involuntarily committed to a psych hospital m. Do i do it anyway?

Backstory: I’m engaged to a legally married man. We’re polyamorous and he’s not leaving his wife. I’ll just be his unofficial wife. My family not only doesn’t support it, but believes my polyamory is a manifestation of my mental illness. I’m moving closer to my fiancé, and they threatened to have me involuntarily committed to a psych hospital because they believe it’s irresponsible and a “manic episode” (I don’t have mania). They said I cannot express that I’m serious about moving, and if I do move, I cannot express the intention to stay there. Otherwise I’m now amissing person with a mental illness.

Because I have an extensive psych record, all they have to do is report me to the police as being incapable of making sound decisions and off to the ward I go until the courts let me out. One time they wanted me to visit them and I said I was busy, so my mom told the police I was suicidal and the cops were at my partner’s door. Only reason I didn’t get committed was because I had text evidence of her intentions. They threaten to call the police if I leave the house after 9pm, if I don’t come home when they want me to, if I go somewhere they don’t want me to, and they’ve even done it because I announced I was going to college. I’m 24 and sane enough that someone wants to spend the rest of their life with me 😂🤷🏻‍♀️

For the reasons above, they don’t know I’m engaged. I want to invite my sister and her long term boyfriend, but I feel like I can’t without also inviting my parents. It’s not a matter of “they just won’t go if they don’t like it” - it’s a matter of my freedom and my rights. They genuinely feel that because I live with a mental illness, I am not a true adult. Oftentimes, the police won’t listen to what someone says once someone calls and says they’re mentally incapable of thinking soundly.

I know I can’t let them know about the commitment ceremony until after I move in September. But I’m really torn. I’d love for my sister and her man to be there, and she’d for sure want to be there. But my parents knowing about it is so risky, and she lives with them.

im 11 months away from the affair, but was told to start picking my wedding party now. What do? 😭😭😭