TN laws on step-children adoption

My husband has joint custody of his 3 children, and has had for over 4 years. His ex pops in and out of the childrens lives, they see her maybe 3 to 4 times a year with no phone calls, except to say she's around and wants to see them. She has not paid child support from the first day, and is abusive EVERYTIME she comes to pick them up (abusive to my husband, and me). We've been to court many, many times over child support, and the abuse.........with NO LUCK! We have learned that she is in prision on drug related charges, and will be there for awhile. Based on her long negitive history, and her imprisonment would the courts allow me to adopt the children even if she didn't want me too?:confused: