Hello,
1) Yes, her father can bring about charges of kidnapping against you. However if the lady testifies before the police that she has on her own come away the charges will not stay.
2) Regardless of the fact that she is a major and willing to stay with you, you can not allow that to happen as , so long as you are married you can not enter into any relationship including a live on relationship.
3) You need to get the divorce decree before you get anything going in the new relationship.