No, I don't think this is fixable and I think you will end up out of your mind if you continue to try and make yourself live the lie you are in now.
I know my marriage will never be the same and I know I will never feel the same about him so is it worth me trying to salvage my marriage
The marriage - the partnership - you thought you had doesn't exist. It stopped existing when he became the kind of man you wouldn't touch with a bargepole, it really entirely stopped existing when you discovered that he was, in reality, this person.
Whether he was always this person and it was always a sham, or whether he did change so dramatically from a lovely, loving husband, lover and friend to a nasty, self-serving cheat who does not really care a fig for you, or probably anyone else, is anyone's guess. Do you believe it's his first affair? I'm not sure I would - ten months? And his behaviour to you was exactly the same, just as loving? And the details - deliberately bringing her into your life, your bed - the peversity of it. That's utter sociopath territory, the behaviour of a man who just does not give a single fuck about the notion of right and wrong, who just does not compute the idea of a marriage vow, or how love works, or how to be a friend. This can't be described as 'a mistake' - it was a demonstration, over a long, sustained period of time, of what his true personality was.
The person we are when no-one else is looking.
It's this you are mourning - the fact (and it is a fact, and the affair ceasing does not change this fact) that he is a deeply unpleasant, untrustworthy liar at heart, and that it is not possible that he feels for you the way you feel/felt for him. You are mourning this loss, and it's a permanent loss. Nothing will make him the kind of man you thought you were married to. He won't ever be the kind of man who would never betray you like that because he loves you. He has shown you that he cannot possibly have been a friend to you in the way any normal person would define friendship.
The other emotion i would imagine is in play is fear. Again, your feelings here are right and correct - your gut instinct. It doesn't matter now what he says - this man you thought was your partner and who you thought you knew. You know better now. You KNOW that he can lie and lie and lie to you and you not suspect a thing. You KNOW that he can treat you with utter callousness and simply not give a shit as long as he is getting his own way. This is a really horrific story - it's so far removed from just an affair. He pushed you into a mental health breakdown when he thought he still had a chance for his lies to stand up and for his affair to continue. I would be terrified to remain in a 'partnership' with this man - common sense tells you that it's a horribly vulnerable place to be, where experience shows that you would literally be a fool to trust in him - emotionally, secually, financially, the list goes on.
You don't say whether you have children - I don't know about your other threads. I would be looking at a way to go forward without him, and that might indeed mean that you stay 'friends' - whatever that means to him - but that you take your life past the corrosion of trying to maintain the fiction that he is your husband. That word means something that he has shown he has no conception of. His use of the description 'mistake' is all you need to think through in order to understand that. I would definitely return to counselling with this plan of action in mind. You clearly cannot stay with the plan you have - it is not working (unsurprisingly, you are unable to lie to yourself any longer) and it will make you ill.
You did nothing wrong. I am so sorry for the way you have been treated. Your posts show what a strong and honest person you are. Turn away from him and take care of YOU.
