Contact AOL customer service to see if they can transfer, they may need permission for the owner, but if you have the login credentials for the account, they can transfer to your account. Here's the contact info:
Here's the number: 1-800-827-6364
You can also use AOL's LiveHelp function by going to the AOL toolbar and typing in keyword: LiveHelp
This is one of the times where I give you an answer you probably won't like but it's the only answer.
You have two choices:
1) Get your ex to call and release the account you are interested in
2) Get your ex to give you the password
3) Get a new email account and start from scratch
Try bribing her.
I know, not the best answer in the world, but AOL won't do anything without the password.
Sorry I could not be of further assistance.
Information Systems Architect
13+ Years of Cutting Edge Systems Engineering, Consulting (Fortune 100 and SMB), and Architecture