If it was determined to be 50/50, then why would the other party think they were going to get 100%? Sure, they can take you to court. You can also take them to court. If the damages are minimal, it isn't going to be worth their time, and they probably won't do it. If they mention it, you can make it clear that you'll be countersuing them, including for lost wages and mileage for being sued frivolously. I doubt they'll want to pursue it after that.
