What if I backed into a vehicle in a parking lot and left a note for the driver, but think the damage may have been caused before the incident?

I backed my vehicle into my neighbor's car while blocked into a parking area by two larger vehicles also owned by the neighbor. I have backed into another vehicle before in the same spot previously and did not leave any damages or marks. The weather was foggy and dark (around 5 am) and I noticed a dent in the door after I returned, so I left my information for the owner. Later on, I noticed previous damages to the vehicle that were not noticed before, such as a broken blinker and scruffs in the front bumper. There are no paint scruffs on the dent, and there are no signs of damage on my own vehicle. My insurance dropped my without informing me a month prior, so I offered to help the owner out of pocket. The owner provided quotes I am unable to read and quoting large amounts. The quotes also seem to have other items listed besides the rear door dent, but they claim it is only for the rear damage. Is there a way to see if I am at fault for this type of incident?