This sounds like a very dangerous situation to me. Depression
and related mood problems can be life threatening because, as in your case, they can lead to suicidal thoughts and self harming behaviors. The fact that you recently drove your car into a tree sounds like a suicidal action.
Serious suicidal thoughts and acting to harm yourself is a medical emergency. I very strongly suggest that you seek immediate medical help. It is probably best for you to go to an emergency room. There, the emergency room doctors
will perform a basic assessment and will probably facilitate an emergency psychiatric and social work referral while you are still in the emergency room.
I think it is very likely that you need to be hospitalized under psychiatric care in order to prevent yourself from harming yourself and in order to stabilize your depression more effectively. It does not sound like you are capable of dealing with this yourself, and the fact that you are already engaging in self harming behavior suggests that out patient management might not be the best option for you right now, at least not until your symptoms are under better control.
Go seek medical help right now!