What should I tell my x friend?

Ok. So I was best friends with this girl(Mia) . We were so close. Then she went to a different school and she became really distant and stopped talking to me and became almost embarred of me I guess you could say. She smokes and does drugs and drink and I don't so we have nothing in common anymore. Then she decided to become a and she started dating my sister's best friend. (My sister's name is Bre and her friend is Niccolette) Now Bre is hanging out with Niccolette all the time and Niccolette is always with Mia. So my sister keeps on hanging out with my X friend who has really hurt me. Yesterday Bre brang Mia and Niccollete at our house and I was with a friend somewhere else. I can't believe Mia would even consider coming to my house! I want to say something to her. What should i say?