I have only read your 2 posts and a few others @Adviceneededrewedding as I couldn't stand all the people on here who are willing for you to totally fuck up your life by telling you to LTB, and either pretending or actually believing that they know your partner, and that he will follow the script to the letter. But they don't know him at all, neither do I, but you do!
I am female and in my 60's, and I am very far from being naive. My first husband left me and our children for someone else, and I have read enough in my life to know what absolute pricks far too many men can be. I also often think I am recognising "the script", but I would never insist to anyone that their partner was 100% following the script, or that even if they were, that the betrayed woman should definitely LTB.
I do not know why your partner would tell you about his encounter with a prostitute at all if he wasn't feeling very guilty and rubbish about it. If he was very drunk, and if this was a one off, do you think that maybe with some couples counselling, you could get over it, and rebuild your relationship together? Of course you can never know for certain that things happened as he said they did, maybe he did climax inside her, and he was too scared to admit that to you.
So it really boils down to, do you think he is the sort to do this frequently, but for some reason felt so guilty about it this time that he has admitted it to you, and as he has owned up to at least part of it, do you think that you can trust him, and continue to love him enough in the future, to stay with him?
I think that as you have no-one in real life to talk this over with, and as every individual Mumsnetter will have their own agenda's - including me, that maybe you and your partner really should have at least a few meetings with a couples counsellor, but maybe your first one should be on your own with the counsellor. If you love this man as much as you seem to, and if he loves you as much as he seems to, then wouldn't it be rather sad to just turn away from your relationship without any proper discussions?
What I don't want you to do, is to look back in 20 or 30 years time, and wish you had given him a second chance. Of course, I also don't want you to look back and wish that you had LTB! If after counselling you do want to give your partner another chance, you can always change your mind if you find it isn't working after a year or two, or even 5 or 6 years. If you decide to separate now, then you probably won't have the chance to get back together again in a year or two's time. Please seek professional guidance, and don't act on the demands of Mumsnetters, again, including me!
I wish you only the best for your future OP. Oh and by the way, my DxH didn't give me any choices, he left me for the love of his life - they are now divorced! 💐