<human>: Give me the gist of the text in a nutshell

I know, I know. 

Curiosity killed the cat as I decided to have a look at some facebook messages between Adam and a friend of his, Ian.

Background: I have been seeing Adam for about a year. We decided rapidly to move in together (to another city) and it has been working great. When we started seeing each other he'd make comments as to how he hadn't seen anyone in ages (neither had I) etc. A couple of times I felt he was estranged or pulling away from me, but he'd explain it as him being nervous. These things have not happened since moving!

Just 10 minutes ago was the setting of my royal fuck-up. Adam's friend Ian is someone I thought I had not met due to him living far away, however we recently realised that I dealt with him being out of his tree on pills and drink one night at work (nightclub security) when we compared pictures and stories. So when I logged on and saw messages from Ian I thought I'd have a look (I know, terrible mistake) to see if Adam had been mentioning this. I went back a little, and all of a sudden there were messages from when we were just newly an item, Adam bragging about "playing two birds at the same time". Ian asking if the 2 girls know of each other and Adam responding that "of course not. they are both complete psychos anyway, I am pretty sure they don't have feelings." 

Maybe it's just guy talk. We never mentioned we were exclusive as such (I just assumed) so I can't be hurt over it. But I know that he'll be home from work soon and I can't act normal. I can't believe he would say that. And he must have been lying about not seeing another girl for some time when we started going out? What can I do apart from admitting my faux pas?
<bot>: partner of one year admits in a facebook message that he was seeing someone else a while ago. Called us both psychos without feelings. I want to leave.