Hey Mr. Oath!
First rule is, don't admit any liability.
Not all accidents are 100% the fault of one driver only.
Reading what you said, it appears there was fault on both sides,.. maybe 50/50.
The other car was not free to proceed until the way was clear, and since a collision resulted, the way could not have been clear, to the extent that driving into that position put the other car in the position of likely accident.
The fact there was an accident is proof of that.
Secondly, since your wife hit a stationary car, it is proof that she did not check sufficiently to ensure that the direction she was about to move in was clear.
It happens to the best of us (except me of course

) and there's not much you can do about it.
We just don't have sufficient eyes to check all directions at once.
Evolution will take care of that in a few thousand years and we will eventually have either eyes in the back of our head or maybe our eyes will slide around to the side of our heads so we can have peripheral vision out the back.
How long can she wait? It might take some time.
Until then, just tell her to be more careful.
Ooops, I mean "tactfully suggest" she be more careful.