mnaha, I am not surprised by anything you have said.
You are tired, stressed, nervous and scared.
Considering all of that, you have done well so far.
I find that 3 hours tends to be my maximum. I get a terrible thirst on, my legs go like jelly, when I get out of the car I feel light-headed and nauseous from hunger.
Always make sure you travel after you have eaten, keep sipping a non-alcoholic drink and keep your mind off of the worries by concentrating on what's around you and talking about it out loud.
You know you have to do this journey, there's no turning back and remember what I told you; you are leaving your anxiety behind you!
When you stop, get plenty of rest and sleep and eat well.
You can do this mnaha.
I am saying this as a person who was in a car crash and screamed every time she got in to a car and had to travel blindfolded for months just to get from A-B. If I can do it. You can too.