<human>: Can you give me a shortened version of the text?

My boyfriend and I have been together for 4 years now going on 5 in August. He asked me to email a summer class assignment for him while he was at work today so I logged into his email and did that for him with no intentions at all of finding anything. I've never been the snooping girlfriend type because of the trust I have for him. I checked his sent folder to see if his assignment I submitted for him went through. In his sent folder were multiple messages sent from him to different Craigslist ads for girls in our area looking to hook up casually and he didn't mind "hosting". My stomach is in knots right now and I don't really know how to approach him about all this. He has never cheated before and I'm not sure if he actually ever met up with any of these girls but the emails he sent them were pretty explicit.. I cant help but feeling like i did something wrong to push him to that. I don't know what to do...
<bot>: just found out my boyfriend of 4 years has been using Craigslist to attempt to hookup with other girls & has an online dating profile.