I [22F] stayed with my bf [22M] of 5 yrs after he showed my nude to his friend

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A few years ago my bf Tom and his best friend Pat got drunk and showed each other in person a semi covered nude without my knowing. Then fast forward years and Pat was consumed by the guilt and confessed to his gf Marie. They worked it out and are still together as did Tom and I. But sometimes I found myself thinking back to that night and wondering if I did an injustice on myself. Won't get into details but I was abused as a child and have sexual trauma and as I've been doing work mentally this situation came up again. I wonder what part is the truth and what is the lie, has he shown others, how many photos was it just the one he showed me? Regardless how he answers I will never know the truth and feel as if I can't fully trust him when it comes to this. We have been together almost 5 years now and have gone through hell and back together and he is in therapy for his issues. But he would've never told me if not for Pat confessing. Not that I know that for sure but he never told the truth until Pat did. I think my only options are to either be honest with him and how it still affects me, break up, or quietly deal with issue on my own like I have so far. Tom gets upset when I bring this up because he feels bad

TLDR: my boyfriend got drunk with his friend a few years ago and they showed each other a nude of their gf (me) and I never knew until his friend felt consumed by the guilt for years and told his gf so my bf wanted to "go down with him"