Ah I see. Fats pull this all the time. My wife's fat fuck friends offered me a calamari off their plate (I ate one to be polite) then charged me for half the appetizers because I "had some". When I protested they oinked and ree'd about how they couldn't keep track and splitting the bill was hard. It was a fancy place and started to get heated so I paid to avoid a scene, but never broke bread with them again. Anyways my point is she may be purposefully causing drama thinking you'll fold. With luck she'll admit to the miscommunication and pay you the $60. I wish you the best!