Recommended books on Internet and Internet Sex addiction

Can anyone recommend good books, self help really, on Internet addiction and Internet Sex addiction.

So far I have seen "Caught in the Net" for Internet addiction but it is quite old, 1998. Also there is "In the Shadows of the Net" for Internet Sex which is also a bit dated and is not surprisingly focused on pornography.

A friend has lost a relationship, gone to jail and is homeless because she was addicted to a fetish/bdsm social network. She chose it over her partner - literally - he gave her the choice and she picked it over him. She then assaulted him in the fight over it, went to jail and is homeless. And not surprisingly, was back on it within hours of getting out of jail.

Any help anyone can offer in books or just plain old advice is appreciated. Thank you everyone.