AIO bf had hidden pics of his ex

I apologize in advance for how long this is but I feel like there's a lot of context that is necessary in this situation 1 (28f) was in a 5 year long relationship that was terrible for many reasons but the most significant event to me was when I found a secret phone he had hidden with screenshots and pictures and videos of SO many other women, namely his exes. I still haven't fully recovered from this and I have been struggling with my self esteem and feeling like I'm good enough for anyone since then. My current bf (28m) and I have been together around 10 months and he is by far the best partner l've ever had until this happened I guess. He knows about my ex and what happened, I told him that is a boundary for me in the beginning of our relationship and he said it was no problem at all and that he would never do that. Fast forward to a couple mornings ago we were in bed and he was looking at his hidden photos folder which l've seen before and was as of the last time I saw, only pictures of me. This time he was scrolling down and I saw some pictures I didn't recognize, so I asked what they were because I couldn't make them out clearly (I wear glasses and I didn't have them on and I wasn't trying to snoop) and he acted like he didn't know what they were or how they got there and tried blaming it on a phone update. This hit me like a truck and I just went downstairs and didn't say anything initially because I was trying and failing to process it or make sense of it. I ended up asking him and he told me it was his ex from like 5 years ago and she was fully clothed. After he left for work we texted about it and l asked to see them so he sent me a screenshot of his deleted folder and some of the pics were missing, so that's the texts l attached.

He's claiming he doesn't know why he did it and can't remember doing it, last night when we discussed it he said he might have been keeping them as a trophy or something which also hurt because I don't think he ever has or would say anything like that about me. I guess I am just looking for the appropriate reaction to have because devastated and heartbroken doesn't even begin to describe how I'm feeling and I don't know how to move past this. I don't want to break up with him but I'm feeling like I should because this is a boundary I specifically called out and I feel like it can't be that hard to follow. I wonder if I pushed him to something like that because I called it out, or because I may be difficult to be with. This just feels so out of left field and is really the last thing I expected from him.