Craigslist Personals

This is really bothering me, but I saw (I know, I was spying, but it was because I had a gut feeling) where my husband was checking out women on the personal ads of Craigslist back when it was around. It was just a few months ago. I found 3 emails on my husband's email account that had been sent to trash, but for some reason I could still see them.
One in particular really bothers me because it was sent to someone and it said "Im at Lowes..text me" and included his cell number. It was in March at 12:52 a.m. It was a night that I had spent at my daughter's house helping her with my grandchildren while her husband was out of town. I confronted him about it and he denied sending it and said he didn't know how it got there. I let it go a few months and came across the screenshot of the email that I had taken back then while I was deleting photos off my phone yesterday. Yesterday is when I noticed the date and time the email was sent, where I didn't the first time I sent it.
To me, it apparently meant that he met up with someone on the Craigslist Personal Ads that night and had sex. I mean what else could it mean?! I haven't said anything else to him since I found the screenshot of the email, but oh, do I want to!
My question is...am I crazy or did something go on, and if so, how do I confront him again? I am almost sick about this.
Another thing is that he is a porn watcher as well.