7 year old sister/sex talk.

So i am currently 20 weeks pregnant with a little girl and my little sister who is 7 won't stop asking me about sex!! asking me Why me and laila's dad hump eachother or if it hurts when he sticks his pp inside of me and if i put it in my mouth?!?! Our parents passed away awhile ago and she just recently won't stop saying things like that i don't even know how she knows anything about sex. i tried to tell her it's what mommy and daddy's do and it's private and not to talk about it but she talks about it daily... any advice? i'm super embarrassed about it 😳