My "friend" is 16 and has a 1 mth old.. well I don't want to ociate with her anymore?

Shes like a family friend and she is 16 just had a baby literally I don't wanna deal with her or her kid ever we went out like once and had to take her kid.. worst day ever I have 13,000 dollar new car and her baby pooped and it smelled horrible and she thought that she would change it in my CAR!! I was like umm NO! you can go to a store or resturant or idc if you do it on the ground but right here in my nice car.. no. So whatever.. she always wanted to hangout with me because all her other friends her age (i'm 19) their parents won't let them hangout with her because she is a bad influence so how do I tell her I never wanna hang out again??