She will never survive in jail. She does not want my help and her boyfriend interferes whenever I try. What can I do?
You can try to pass on information to your daughter's attorney about her condition. She's an adult, so as long as she's mentally competent to stand trial, she can refuse your help - even if you hire an attorney to represent her.
You say you "think" she's mentally ill. What do you base this on? I'd suggest you contact her attorney and let them know your concerns, but don't expect them to discuss the case with you - they have a duty of confidentiality to your adult daughter.