Be honest. Tell your parents what you did and insist on paying to fix it. Then follow through and pay to fix it, even if it means getting another job, working more hours at a current job, selling something, whatever.
And on a mostly unrelated note, don't beat yourself up over your parents paying for your diabetes meds. If they're like most caring parents, they aren't holding that against you. Don't feel guilty about them wanting to make sure you're healthy. Improve your job/career, make more money, and someday pay them back if the money bothers you. But don't feel guilty about a parent helping you get medication you need to live.
Just tell them you'll pay for it. Plus pay attention to your driving. Get some estimates.
Take $1500 to a good body shop. They can make it like new.
You need a body shop and it could be pricey. Since I can not see it I can not give you an estimate.
You see, I already dinged up my own car and my parents had to pay for that. Now I've gone and dented my dad's truck backing into a lamp post. They already pay for my diabetes prescriptions and I don't want to bring the news to them, costing even more money. How can I fix this myself and how much will it be?