I was in your position pretty much this time last year, but with the roles reversed. That moment you find out, is the worst kick in the bits you can ever have, nothing prepares you for it.
It's the realisation that for you, the person and relationship will never be the same again, the trust is eroded and you feel you don't know them anymore. That change is on them, it's their extremely poor choices and actions that have caused it, so no matter what the excuses, it's on them, not you. It's not your fault.
My mental health went rapidly down hill for a long time, but I'm better than I was, but I'm certainly not the person I was and probably never will be.
Do I know everything that happened? No, I know I don't, but the honesty would be very much appreciated. Do I want to know? Well, yes, I'm owed that.
Only you will know if you can work through this and carry on. It will never be the same again though. If you do keep going, just remember, it's you that is in control and if at any point you think, no, this isn't for me anymore, you can walk away with a clear conscience, knowing you tried your best.
It's hurts like hell though OP.