Legal Question in Traffic Law in Illinois

You can settle for the 80%, argue for more, go to your own insurance, and possibly sue the other driver.

The question will be whether you created an unreasonable risk to the drivers behind you by slowing to 5 mph, especially around a curve as you admit, and whether the driver who hit you in fact tried to avoid you as a "last clear chance". Because if you sue her in Illinois the rule here is "comparative negligence", and those may be her defenses. Depending on other facts, you could wind up with less if a court felt you were more at fault -- say 30% or 40%. And you may be lucky if the other driver has no personal injuries either.

As to your insurance there's a police report and you're involved. If you proceed accepting her insurance your insurance company will still have a right to require you to disclose the incident for a future renewal and your insurance company may have the right to bump your premium even if you weren't at fault, but just because you were in an accident and even if you didn't claim a dime. So you're like most of us - darned if you do and darned if you don't.

Since there may be additional facts that could affect the outcome and this is not intended to be that kind of forum, this answer is not intended as legal advice as such but only some of the things to consider in context of the total situation.

I agree with Mr. Messutta.

I also do negotiations with Insurance Co.'s regarding property damage for a flat fee of $500.

This includes drafting and responding to correspondence but it does not include representing you if you decide to file suit.