Who says we human have only one heart? I think we have the capacity to love more than one person at any one time...one heart for one love
If a person has the maturity to control one's emotion then he/she can compartmentalize his/her feelings and can enjoy the fruit of loving and caring for more than one person.
I think Ling is one such person and if you cultivate her well then you can keep her loving relationship for many years to come. Why I say this? Because first she knows you are married and love your wife and second her initial philosophy is never to be a home-wrecker. But since she found illicit love she is willing to accept from you what you can share with her without expecting more. Perfect fb material.