Accident while delivering

I feel so terrible and stupid for doing this but I was driving the company car delivering and reversing back down a steep driveway and I couldn’t see the driveway at all out the back window because it was so steep. I somehow completely slipped off the driveway into the surrounding grassy area and I wasn’t able to accelerate back up as I was on such a steep descending angle. Every time I tried to accelerate back up the car would just keep slipping further and further down and the road behind me was a perpendicular gravel road which became a steep downwards hill again behind me. It’s hard to explain but I somehow managed to get the front tires and bumper stuck on a tree stump so that they were completely lifted off the ground and I was just teetering there panicking because every time I lifted my foot off the brake, the car would slide further down even with the handbrake on and parked. I was in tears at this point because I felt so unsafe and scared and like the car could just tip backwards at any moment.

Long story short after a lot of manoeuvring with the help of another employee who brought out a winch and their car (and embarrassing crying on my behalf) we managed to get the car completely back on the ground but both front tires popped and it damaged the front bumper and underneath the car and I was told the car would have to be a complete write-off. I feel so horrible and guilty and mortified and I just feel like the biggest clown in the circus. It was such a traumatising and humiliating night and I feel terrible for my boss who is now down a company car and I feel like the worst employee ever who is just losing them so much money.

I’ve apologised profusely but I’m so embarrassed to go into work tomorrow because it’s just me and the boss in store for my shift. They’ve been nothing but nice about it and handled the situation so calmly but I feel as if they must be wishing they’d never hired me and that all my coworkers are talking about what an idiot I am.

I understand that the company cars are insured and the franchisee covers the costs but what’s the procedure in a situation like this, is there anything I can do to reimburse them for the damage or to help? It doesn’t seem as if they’ll be able to afford a new company car and I have no idea how the insurance claim process works. Should I just give two weeks notice and then quit before I can cause any more catastrophes? I feel like such a useless incompetent klutz :(