The key part of endurance/performance training has to be "going beyond yourself" - doing more than you can really cope with. Whatever aspect of endurance/performance you are busy developing, doing too much of it is what you are working towards. And sometimes you achieve that - you do too much.
Well done - you have achieved the central goal of your training! Many people never really push themselves, they pootle along well within themselves and presumably are happy to keep at whatever level they are at.
For ones who push, who aspire and want to do something bigger than they could ever imagine doing then getting to a point of exhaustion is the goal. But it involves real pain. You are going to be tired, to be exhausted, to be on your knees. And that's good, despite it feeling so bad. Your body is going to take the hint, its going to come back stronger, and you are going to be better.
Italian events and European climbs