Hi! I'll be glad to be of help with this issue.
I can imagine how frustrating this situation must be for you. You are clearly a "normal" person and it's as though you've just found out that your boyfriend who you've thought of as normal for 5 years is not. That is a big shock. And you're right in one sense: spending time in jail over indecent photos is not "normal"; it's criminal and it's awful.
The problem is that you've known him for these 5 years and now you're unsure if he's been telling you the truth or hiding things from you, behavior around pornography, etc. And also you're unsure whether this is a curable problem to begin with, even if he's been "clean" for these 5 years.
The answer to the first question is difficult. It's very tough to really find out if someone has been hiding a porn addiction. The answer to the second question is also difficult but you need to know that a person can live a healthy, productive life after such an event.
The variables you need to learn about are what was the nature of his activities that he actually went to jail for them. This was clearly more than a one-time look on the internet at some pornography of children. You want to hear from him what happened. But you also want to see the official court statements if at all possible or some type of official record to see if his statement matches what the police and court said happened. If he minimizes, that is certainly some indication that problems may remain.
The other factor you want to pay attention to is how he treated the problem. By that I mean what type of treatment he got. It's true that jail by itself can convince a person not to repeat crimes. But not often. Repeat jail time is much more common. And with sex crimes, the literature is clear that treatment is vital for there to be proper management of urges and drives in the future.
So those are the things to pay attention to. I don't know if the internet was involved for you to be concerned about looking at his computer's history. Though that is not foolproof by any means, spot checks can be useful.
I know this discussion by itself makes you cringe and feels awful. As I said above, it's not "normal". But life is really quite complicated and he may be a good person as you've always thought.
Okay, I wish you the very best!
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