Some options have big spreads. What was the spread when you got into it? Crossing the spread has to be taken into account as part of the price of the option.
To answer your question about closing it, you can either close each side separately ("legging out") or, since you're using IB, you could also use Spreadtrader to put it into the market as a spread. Either way, you should try and use limit orders, maybe split the bid/ask spread so you don't get screwed on your fill.