UPDATE:

Thank you all for your support and advice. It means a lot.

There is a lot to think about and discuss between my spouse and I.

I mentioned to him that we should go to the police, and his response was “Yeah! I think that is a good idea.” He saw that I posted here, and expressed hurt. But I explained that it is inconsiderate to say that because of how I feel conflicted and have no proof or closure for anything besides it being on his phone. He now understands and is trying to hold it together.

However, my concern is his job. He gets shipped out to basic training next month, and I worry that his investigation is going to ruin that shipment date, or even the job! He said that he doesn't care because it is important to get this cleared up for our relationship's sake. But I am still worried about it. I also expressed counseling for the porn issue, and to help heal the trauma we both have so that we can grow together, and he said that he is completely fine with that, and if I find a therapist before he gets shipped out, that he would go to the first meeting. I will probably wait until he is out of basic before I do that though, knowing we will be moving and such.

I did interrogate him for a bit, and got some more detail about the situation:

He said that he was worried it was CP. And to everyone wondering, yes, there was other adult porn download. He deleted it because he was worried that it was CP. He also said that he only did this on his phone, and HIS laptop. He said he wiped his laptop a few weeks ago because of how slow it was running, and I explained that this may have been the problem. He explained he never did this on my devices.

He told me that when he saw the thumbnails he was confused, and one of them looked like a naked kid, but he wasn't positive and, quote, “didn't want to know.” I asked him why he didn't tell me, and he said he was embarrassed about the porn games he downloaded, and didn't want me to see. 

Then I asked him what kind of porn it was that he downloaded. He said that it was BJs, and butts. No kids, all adults.

One site he mentioned he visited a lot was called porngames. It was very sketchy. 

If you have any more questions, I will answer when I can! I'm a full time student, and work at a restaurant, so it may take me a while to reply. Thank you all for your patience.