Drama for your...

For reference to this long rant (buckle up),

I have a first cousin who I used to be extremely close to. We are the same age, we went to the same college, did literally everything together. She started dating a guy a few years ago and things changed. Not just between her and I, but the entire family. To make a very long story short and to avoid spilling details that aren’t appropriate, this guy is no good - I’ll leave it at that.

I’ve posted about this before - we downsized from around 200 to 75. I have included our family and our closest friends in the guest list - we are more than okay with this. This includes my estranged cousin, her brother, and her mom and dad.
I recently sent out my save the dates. Her mother, my aunt, texted me to tell me she got them and that she went ahead and RSVP’d online for the family - yes I know, it’s way too early but I somehow left my RSVP tab public on accident. She also mentioned in this text “you only have 4 of us on your list, but just know that both kids will be bringing their boyfriend/girlfriend so there will actually be 6 of us.” - mind you, her brother has ~literally~ been dating his current girlfriend for less than a month and I haven’t met her, nor seen him in over 3 years. And in all honesty, I don’t want my other cousins boyfriend there at all. Nor does any of my other family. This is one day that I think I’m allowed to do that.

I’m not necessarily asking for advice, because I’m fully confident that this is totally out of line. Our wedding is very formal and we are sticking to a strict count, mainly because our venue isn’t huge and we’re paying for our wedding ourselves. I’m more or less asking if I’m wrong in telling them ‘absolutely not’. Not “because Covid”, just because “I said so”. This part of my family is fueled in drama and I know it will blow up either way.
Thanks for reading my mid-week rant!