Husband's gd living with us & she's now 18

Hi. My husband's gd lives with us since she was 3 months old. He took care of her, but he doesn't have legal rights. The father should've had custody of her, but since he is unable to care for her my husband became her primary care taker. She is now 18. My problem with her is that she does nothing at home & doesn't follow house rules. My husband and I have 2 girls ages 11 & 3. I do not think my husband's gd is a good influence on my kids. She has snuck alcohol from my house, smoked/smokes pot, drinks & just caught her having sex in my home. My problem is that my husband does not want to send her to her father who now lives in Florida. What are my legal rights as his wife? I really want nothing to do with his gd & I've been dealing with the situation for 12 years now & I'm at the end of my ropes. Please advise. Thank you.