My question involves an accident that occurred in the state of: Kentucky

I was driving down a 4-lane road (2 driving lanes in the direction I was going plus parallel parking spots). I noticed a spot to parallel park in front of me, put on my blinker, and pulled into the spot forwards since it was big enough. I wanted to get closer to the curb, so I put my car in reverse and turned to the right. While I was reversing, a car in the right lane drove by and hit my front left bumper. His car was just scraped but my bumper is more damaged.

I didn’t call the police, but a witness gave me his name and phone number, and I have the driver’s insurance info. He didn’t take mine, but he has my phone number. He is urging me to resolve it without insurance and essentially offered to split it 50-50. Who is at fault?