It is NO fault policy in Ontario. Insurance company is responsible for the insurance of the car the company insured. This both parties don't have to wait whose responsibility before you have your cars fixed.
The policeman didn't give you a ticket doesn't mean to the insurance company the accident is NOT your fault. Since you were rear-ended by another car at the back, your responsibility is 50 %, the other 50 % goes to the driver at the back. To the insurance company, you failed to provide a safe distance between your car and the car in front, safe distance means when the car in front makes a sudden stop, you can stop without hitting the car in front. And policeman can issue a ticket "Follow too closely"
You should expect your insurance to increase quite a bit (since your car is total loss?), and it takes seven years before your insurance will be lowered back to the amount you paid today. The driver who rear ended your car has to face the same destiny. To the insurance company, what they care is how much they spent to cover accidents. A ticket is a freebie to them to increase insurance (at no cost to them).
Luckily, there is nobody hurt!