Texting and sharing nude pictures: Adultery?

Reading from LadyBing: "Is it Cheating ?", has given me the courage to present my own problem. We have been married for 11 years and have been going through some sexual problems for the past two years. For more than two years now my wife is getting less interested in having sex with me. She even went as far as suggesting that we should stay without sex. She told me on one occasion that she does not have any feeling for me: that the flame is no longer there. Each evening when I go to bed (around 10pm)she goes on internet and stays late, most of the time up to past 1 am. About three weeks ago I discovered that all those nights she has been texting with a man she met during a professional exchange visit early 2011. They have been sharing everything (pictures with family, vacation pictures, daily frustrations at work and at home, their respective sex lives with spouses etc) and usually make sex appointments on the internet. At each appointment they take and share current photos of their intimate parts (vagina and penis). She addresses him "my lover", "my other husband who gives me what my husband cannot give". The texts describe very intense emotional, sensational and erotic (sexual) scenes. They are very committed and passionate, staying on the internet for an average of 3 hours and at least twice a week. I have been devasted since I discovered it. I confronted her and she said that they stopped it 3 months ago after realising that it will not take them anywhere. I asked her to give me her email password so that I can really make sure that it has stopped and she refused with such vehemence. Each time I try to talk about it she is so defensive of her (internet) lover and gets very upset when I make any derogatory remarks about the lover. The worst part is that she does not show any remorse for what she has done (or is still doing). The only thing she ever said is that she is ashamed for falling that low. In July 2012 during her vacation she travelled alone to the city where the lover lives. The two days she spent in that city where approved by the lover in an email of May 21, 2012 and the lover promised to meet her during her stay. She maintains that they did not meet during her visit. There are so many things that do not add up and I am convinced that they met. It is really stressing me up and I donot know what to do. I have not been able to work normally since my discovery. Each time I try to forget it my mind keeps going back to the nude images and the erotic messages. I feel ashamed, abused, used and debased. Can I ever trust her again? Is it not adultery? Should I or should I not file for divorce? It is eating me up so badly!

Put the internet to work for you. via Personal Recipe 2629979