MY STBX HAS BEEN TALKING TO A 16 YEAR OLD GIRL

I found out that the girl from the cell phone bill is only a sophmore this year in high school! My husband had been talking to her late at night while I he was in the bed and I was on the couch. At first he denied that I had heard him talking to anyone on the phone one night when I opened the door and asked him. Then, I discovered pictures of him and another girl, both mostly if not all nude, on a hotel bed on his myspace page only days after he left. When I confronted him about the pictures and talking on the cell phone in the bed, he admitted it. He only admitted to it being her, not the 15-16 year old though. Looking back at the cell phone records, I noticed that her number was on there early in the morning (before she left for school, and while he was at work), and late at night. 

I am so disgusted, more than ever before. I suspect that my husband has a sexual addiction beyond his addiction to pornography. This isn't the first time that he has talked to an under age girl. Only this time, I recently had a couple of people tell me they had seen my husband out with another girl at the bowling lanes with a couple other people. I don't have proof that they have ever been physically intimate, but I suspect they have. He had been spending  a lot of time at the house of the other friends who were with him at the bowling lanes. I just didn't think that they would be stupid enough to to knowingly let this go on.