I don't think you should be too hard on yourself - that's a helluva ride you've done even if you didn't make the whole thing. Also, don't forget that you've been escalating your distances pretty quickly over the past few months; you were bound to hit a wall sooner or later. I'm sure you have it in you to achieve this sort of ride, but it's also good to know when to bail for the sake of your health. Well done.