Well, if he wants this to be treated as an addiction - i.e. he is a helpless victim to his cravings - then what is he doing to treat his addiction? Cybersex addiction is considered a real addiction.<br />
Has he seen a professional? There's no rehab for too much cybersex, but there are certainly psychologists who can help treat him.<br />
Has the internet been canceled or a net nanny put on that blocks his favorite websites? <br />
I could think of other things, but is he doing everything in his power to stop? <br />
If the answer is no, and you can't get him to try anything more than promising not to do it, leave him. You are not obligated to help him conquer his demons. You're doing what you can to look after him and he is obviously not returning the favour by looking after you, and you deserve better than that.
I agree - he is addicted and there is therapy and there are support groups that will help him control it but it has to be his choice. Life is too short to be competing with a pixel - think carefully about your own happiness and decide.
I would also recommend some counsiling .
I am not going to tell you what do but some say cyber cheating is just as bad as real life cheating. I would recommend marriage counseling