Determination of Fault: My Friend Accidentally Hit a Car's Bumper While Backing Off

So my friend was backing off from a parking lot as following:

ㅁㅁ = her car
ㅡㅣ orㅣㅡ = parking lot

ㅡㅣ . .ㅣㅡ
ㅡㅣ . .ㅣㅡ
ㅁㅁ ->ㅣㅡ
ㅡㅣ . .ㅣㅡ
ㅡㅣ . .ㅣㅡ

Then suddenly a car came in, and she accidentally hit the car's bumper as following:

ㅅ = another car (front side)
ㅁ

ㅡㅣ . .ㅣㅡ
ㅡㅣ . .ㅣㅡ
.ㅁㅁㅅㅣㅡ
ㅡㅣ. ㅁㅣㅡ
ㅡㅣ . .ㅣㅡ
ㅡㅣ . .ㅣㅡ

She says that person claimed to have honked well before, but she says she heard it just as she hit his car. She also questions why he was in her way when she was backing off. Also, the distance between the lot she came out of and the place the accident happened is almost 2 meter long, just as the illustration shows:

ㅡㅣ . .ㅣㅡ
ㅡㅣ . .ㅣㅡ
ㅡㅣ. ㅅㅣㅡ
ㅡㅣ. ㅁㅣㅡ
ㅡㅣ . .ㅣㅡ
ㅡㅣ . .ㅣㅡ

She also questions why he wasn't backing off when he had a plenty of time to back off, only to honk when she was about to hit him.
There is an unnoticeable dent in her car's back, but there is a visible dent (* represents the place of dent) in his car's bumper:

frontㅣ二 二 二 二 ㅣback
(二 * 二 二 二 二 二 二 二 )
. . ㅇ . . . . . ㅇ . . .

According to her, her insurance company told her that the man's car's dent showed that the man was at a stop when she hit his car.

I want to help her out, so I am posting here to see who is at fault. If she is at fault, how many percent is she taking responsibility?

Determination of Fault: My Friend Accidentally Hit a Car's Bumper While Backing Off