I don't think there is any rush to make a decision, you can always give him a little time to see if he progresses. But if you do walk away, you are not a failure.
And you wouldn't even be walking away, Kris. You would be moving on. Understand?
Try doing this now, while leaving the door open for your H, should he someday wake up and choose to actively work on your M together.
Getting over a painful experience is much like crossing monkey bars. You have to let go at some point in order to move forward. ~ Joseph Campbell