Thank you for posting. I'm sorry that I don't feel I can just reply simply with, "I think you should do this...."
Firstly, I want to acknowledge what an ordeal (even that word doesn't capture it - you said 'hell' and perhaps that's the only apt description) you've been through (and are still in the midst of) and it sounds like there are not many people around you (including your partner) who are acknowledging what you're going through. Your partner has put you through this immensely difficult experience and is assuming that he can just pick up your relationship where it left off! Has he acknowledged what this has been like for you; how you've suffered ostracism, your own anguish and, on top of that, the financial implications of being left alone (all of a sudden, I imagine) to look after yourself and your family?
I'm so mad (and sad) that you've been the one to suffer abuse and isolation from those closest to you. It's not you that did anything wrong and yet you're the one who gets harassed and by your own family! Do you have friends or anyone who is supporting you in this? (I really hope so).
It sounds like you have empathy for the abuse your partner suffered as a young person. It's so difficult, I think, to hold seemingly conflicted views at the same time - to have compassion for the pain that a person has experienced and to want to support them through the abuse they have experienced while also holding them accountable and responsible to not further perpetrate abuse of others. Your partner needs to take responsibility for this, himself. No matter how much you may want to help him, he has to make the decision to get help for himself and to be fully accountable for his abuse of children through accessing child pornography.
You asked, if anyone here has forgiven and stayed with their partner. Personally, I didn't and I haven't, yet, met anyone who made that decision. I didn't leave my partner immediately. I helped him to access a psychologist and I wanted him to want to do something to stop what he was doing. It became clear to me that he wasn't going to stop and I left. I can't say what I would have done if he had got help and I really believed that he had stopped viewing child pornography and would never do anything like that again. I know there was no way I was ever going to have children with him. Even aside (which is a huge aside) from the child pornography, there had been so many lies (in his covering it up) that I couldn't have trusted him again, ever. I don't think I could have continued any type of relationship knowing the breadth and depth of the lies I had been told for such a long time.
I don't know if I'm reading too much into your post (and do tell me if I'm wrong) but the sense I get is that, perhaps, you're feeling pressure from others (including your partner and children) that you ought to forgive him and carry on your relationship but that this isn't what you might want for yourself. You are still suffering because of your partner's actions and have had a horrific year and it doesn't seem fair to you that you ought just put that behind you and carry on as if nothing has happened?
I wish I felt that I could give you specific advice on what you should do (and maybe others on the forum might have an opinion) since this is what you've asked for.
When is your partner due to get out of prison? Have you considered talking to a professional counsellor about the questions you have posed here? I'm certainly not saying that everyone in this situation ought to see a counsellor as I think it’s important we are allowed to grieve in our own way and time without necessarily going straight to a professional to get 'fixed' (though others on the forum have found counselling immensely helpful). Maybe accessing a counsellor could be useful, for you, since you have a specific issue / question you want to work out for yourself and using the strategies in counselling could be a tool for you to work out what is right for you.
If you do seek out counselling, or professional help, please ask for recommendations or do some research as I’m incredibly wary of some counsellors who do more harm than helping. Personally, I had one horrific and one really positive experience of counselling. If this is something that I can help with, I’m happy to do some research to help you find someone appropriate if this would be of any help.
Sorry for such a long, rambling response and not directly answering the question you posed. Hopefully, others might add their perspective.
Please do feel free to come back and reach out if you find support here.