Still struggling to find nuance in my fiance's confession

for the longest time I was believed that anyone who commits this unspeakable act (sexual assault) should be killed outright or imprisoned for life full stop.

then my fiance comes to me with this. says "this is what I've done. I have not hurt someone like this in over a decade, when I was 15." and he gives me the power to blow up his life. This man with whom I've lived for 2 years, dated for nearly 5. This man whom my family adores, and my friends admire. And he says to me "I committed this unspeakable act over a decade ago. I stopped myself. I restrained myself in every way, pushed differing media and perspectives into my head until every thought of that unspeakable evil was gone. I put in the work to stop myself."

But god it felt like my world imploded. What now? Nuance. Shades of gray. I know it sounds so dramatic but it felt for me like foundations crumbling and fury still ravaging what little self-esteem I had left. So much of my trust broken, in myself and in him.

I don't know if I still trust him. My therapist says if I want this relationship to continue, then I have to. I have to trust what I've seen. I trust what I've felt. I trust his patience and gentleness when I am unraveling. I trust his generosity that would take him across multiple state lines so his friend can start a new life.

I trust my friend's head on his shoulder. I trust my parents who know everything and still don't think he's a bad person. I trust my best friend gently bullying him like an older sibling would. I trust his hugs and his laugh and the way he adores my quirks.

I trust how much he still hates himself. I trust that any detailed discussion of his unspeakable acts sends him to the toilet, makes him violently ill. I trust the 5 years he has now spent in therapy, no breaks, few skips, and a well-educated professional whom I've seen knows her shit and does it well. I trust that he confessed everything at all. He could've gone to the grave with that secret. But he said he wanted me to know him before we got married.

I am having to take apart a short lifetime of black-and-white thinking. Part of me still hates myself for betraying my own deeply held beliefs. But I am also trying so hard to remember that just because a person does a bad thing does not make them a bad person outright.