Is this cheating?

Ok so basically my husband left to boot camp about a week ago for the Army & today I was on my laptop where he has all his emails logged in & I was trying to see if he had any emails saved that had info about his MOS & what not so I go to his sent emails and I find one with a bunch of attachments that he sent to himself & it was a bunch of selfies of this girl. The email subject was LM & after lots of Instagram investigating I found her & now know that LM are her initials. I couldn’t find any interactions or anything between them but I don’t have his phone & I have not felt the need to snoop through it any time within the last year so I don’t know what could be going on. Regardless why would he have all these pictures of this girl saved ?? Also he doesn’t even follow her on Instagram but liked one of her pictures. Basically once I get his address and can write to him I want to send a letter saying how upset I am and asking why he would have her pictures saved I mean obviously it is sketchy and any explanation he gives is not going to make it ok. I feel like an asshole to bring it up while he is already under so much pressure being at boot camp but wtf am I supposed to do?! I can’t just go get the next 2 months writing to him & telling him how much I miss him & wait until he’s back to bring it up? It’s bad enough I suffer from anxiety now I have to deal with the fact that I can’t even confront him about it.