Picture of a girl on my boyfriends tablet?!!

I was looking threw my boyfriends pictures and found a album called "download" that had a picture of a pretty blonde girl. I'm 8 weeks pregnant and I thought we were good so this shocked me so asked him who it was and he said oh from this email look (he gets emails from a dating website he used to be on and they wont stop emailing him apparently) and I didn't want to look because I was pissed I'm sure any girl would be. So then he deleted it, then deleted it out of his trash before i could even look! Last night I told him it was bothering me now he came up with this story he clicked on that specific one because it was the only one with a picture, how would he know without opening it? Then came up with another idiotic story saying that when he was at lunch he opened it to show it to one of his coworkers for "them to see" what do you ladies think? I've been cheated in the past and it just seems fishy to me or maybe I'm hormonal and crazy but seriously! Help! Oh, and these past two days he usually ALWAYS texts me during work and nope. He's been working too hard, but his Facebook says he was online 30 minutes ago and I'll check again and he was on 5 minutes ago but hasn't responded to my texts... :(