No, it is not his fault his wife chose to cheat. But he's all sucked into that cheating bubble thing on that tier of their relationship right now.
You also cannot make him "heal faster" or "save him" from hurtness. His healing process is however it needs to be for him.
At the same time... that does not mean YOU are not alive and having wants, needs, limits of your own. Your own tier of relationship with him is not thriving.
It's basically your call. Can you endure here in the sidelines waiting? Or are you tired of the wait? It's hard to tell from a distance and really... it's up to you in the end.
I empathize that it is hard to discern right now... but it's still your call to make. Only you know your limit of tolerance/patience levels.
I'm sorry its rough going. I do read your post if that's any small comfort -- someone sees you struggle.