You are not 50% liable for anything... use two words on the insurance company "Good Faith"... Tell them that you do not accept their finding because the officer cited the other driver.
Also, why isn't the other driver's insurance covering the accident? Don't settle anything until the guy's ticket goes to court, once he pays it or is found guilty, the burden of proof for civil court is met and he becomes 100% liable in a civil suit. All you'd have to do is file it and the judge will award in your favor. Accept nothing until then or you're SOL.
Good Luck,
Joe