Detachment is a thing that helps. Not to be cruel, but you must own the being betrayed as much as the wayward owns having betrayed.
You must regain your center and direction, out of the illusion of being in two through life, no you are not, you are alone following your own path. You only have yourself and yourself is the only thing you have influence over, in absolute and right now.
When you find your center then you have no problem in allowing others to walk along your path with you.
You are open again to allow someone to enter your work too, no longer afraid of betrayal, if that happens again you keep walking and don’t look back.
When you get there you can finally even allow. You’re wayward to rejoin your side, maybe is just harder to allow them in because the past, so you are more wary about them than others naturally.
But if, and the if is important, the wayward wants to keep on your side and with time, now that you are detached, you can see they are truly different, maybe slowly things can get intimate (as in bonding) again.
Mind you, is a big risk, you are just so much stronger and more detached so you accept already that this partner can betray you at any time, they did already so they can do it again, they proved capable of it beyond any doubt. So even if the feelings are there it. Might require more time, perhaps even your entire life, it will be a process of patched bonding, not the natural and easy way as it used to be, no with this person, it will require constant work and boundaries.
But is not impossible.
You have been destroyed deeper than most thing could break a person. You must re find yourself before allowing someone else. That goes an order of magnitude higher if instead of someone else the partner is your wayward.
It can be done, is not as easy as a clean relationship because you can’t do it unless you find your center first (as in really do it, not just pretending).
this burden was un unrequested but you have it and you will carry it willingly or not unless you radically change path.
Doesn’t mean that he can’t have feelings for you, they might be there, is just a hard path to walk. You weren’t given the choice and somehow you chose to not drop it all. Only time can tell if it can be done or at some point the weight is becoming too much.
The mere attempt to carry it on should say to you something about how your partner valued you when they chose you.
You can’t make it lighter either, it’s outside of your influence. You can avoid making it heavier and be considerate (Simms your case) but you lost the power to lift it from your partner’s shoulders when you chose infidelity. Relief and help is forever out of your hands now.
You have agency on you alone. Healing your heart and mind is the best thing you can possibly do. And a "help" in other ways: can’t lift the burden, but maybe just maybe, can make it feel "worthy " to carry it