Boyfriend is trolling craigslist for sex

So I have done the worst thing someone can do and that was look thru my boyfriends phone big emotional mistake on my part. Not only is he looking for couples to hook up with but other females as well. Last night I wrote back one couple telling them that he has a pregnant girlfriend and a son from a previous relationship that I take care of and let them know that further communication with him would result their pictures and emails exposed to the world. I realize it isn't their fault it is more on him then anything but I am pregnant and just over this crap. So today he tells me that he knows I was on his phone because well I'm sure the couple emailed him back today telling him about my email. Anyways he says that he is just curious and likes talking about it and getting pictures but why would you try and meet up then? I'm not stupid so I called him out and told him he needs to be honest and open and his response was "okay" I mean wth what does that mean he's gonna stop or just trying to make me think he's gonna stop looking. I've been told guys do look at the website but never answer so I'm confused, hurt, and pissed. Also I have cancer and am a high risk pregnancy this stress isn't healthy for me or my baby. I have never felt so unwanted,attractive, or more gross about myself then I do now. I've also been losing weight and now I just let the world bow I'm fat and unattractive now so I don't have to hear it from anyone else....advice anyone