Glad your safe!! Sounds harrowing.
I made a similar call once, saw two cars that were obviously racing each other. The operator said she had a number of calls about it already. About 30 miles further up the Interstate we saw a squad car had one of the drivers pulled over so I pulled over in front of them and told the officer that yes indeed I was one of the callers and the car he had was certainly one of the racers.
But what was WRONG with the woman you saw? You said that she looked like she was about to pass out, but in another statement when she took off from the cop it sound like she was evading him purposely - not like someone about to pass out. Was she indeed trying to evade the police???