<human>: Hi all. I'm not usually a reddit user but a quick google of my problem led me here and I hope you can help.

I have been going out with my boyfriend for just over 3 years. July last year I moved 300miles to be with him and just before Christmas we got an apartment together (we previously stayed with his Dad while we looked for a place).

Everything is going great, but I just found something on his computer that I really don't know what to do about. I want to make it clear that I didn't go looking - we often use each other's devices and I fully trust him and have no reason look for anything. I wanted to use his mac for Photoshop - I opened Spotlight and searched 'photo' and although Photoshop was the first option, my eye spotted some naked photos further down the list. Thinking it was one of the many photos I had sent him while we were living apart, I clicked on it to see which one it was. My stomach dropped as I realised it was actually of his ex boyfriend. The date was on the photo was September 2011, when we'd been going out for over 18 months. 

I obviously need to speak to him about it, but I have no idea what to say. Or even what I should do after that. There's no evidence that anything has happened between them (or anyone else) since then, or even before that, so it seems stupid to throw everything we have away, but I don't know if I can carry on trusting him. And what's a relationship without trust?

Give me a shortened version of the text
<bot>: I accidentally found some naked pictures of my boyfriends ex on his computer and I don't know what to do about it.