Houston can't help me with this problem 😫

K
Ok we have a problem 😶.
I'm in my third trimester so trying to navigate this situation.
I told my Mom it would be my Husband and me in the delivery room. My Mother is very sensitive, and while I know many would say "tell her eff off", that's not possible when trying to keep your sanity because you'll hear about it - forever. The real reason is she isn't good at being positive at all... lol. She thinks she is but she simply wasn't with my first when in labor "You think this is bad... when I had your sister" or just comments about how my child looks like my sister or whatever right after giving birth 🙃. SO I told her it was because it's my mother in laws first grandchild, and since she is out of state and is a teacher making her ineligible to experience her grandchild coming into the world, that I didn't think it would be fair if she got to as well.
So she asks nearly every few weeks and I repeat this. Until the other day 🙃. She asked me in a way that sounded like she was asking if she and my 18 year old sister could come in PRE-BIRTH. Like during "the waiting game". I figured "well I mean we'll be there hours and if I need to I can tell her when I start feeling bad and need them to leave". Right? So I say "sure" and she starts cheering and talking about having my sister come into the room, and even packing a bag for my first born to come in during (not actual labor) 😶. At this point I realize that a mistake and miscommunication has been made. I try and save myself with "Well these doctors haven't been fans of too many people other than Dad in the room for appointments so I'll have to check with them first, because it might not be hospital policy". I arrive at my Dr's visit that same day with her in tow because she wanted to hear the heartbeat and this is the only appointment my Husband couldn't make, thinking "I can save myself still". Somehow I didn't think to think she would literally ask my midwife. Which she did. And I know it was likely an accident but the midwife goes "Oh no we let everyone and anyone in the room, were totally ok with it" and when she catches the look on my face (probably petrified) she says "- but only if Mom wants to" and you can tell she feels so bad lol. 
I know I need to find a way to say something now. And in a way I don't have to hear her lament about it right up until delivery because I will freaking snap out. But today my sister asked if she could cut the ambilical cord, in front of my mom, and my Mom got overly excited and started cheering that on which I said "you'll have to ask my Husband because it's his first child and that is up to him". Which I could already see the sap flowing around. PS she's already told my child she's going on some adventure in my hospital room 😫. 
Seriously could cry at this point because we were solid and now it's unraveled based off a play on words. Hate myself😑.