What happened on last season's finale of Medium?

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One of my favorite shows over the past few years has been Medium (Patricia Arquette). And, even though it's not a show everyone can identify with, I found it rather refreshing to see a story about an ordinary mom who saves the world (or at least her city) in her spare time. Sounds like my life. Last year, it came back on during November. So, I was wondering if they were planning to put the show back on later this year. Does anyone know whether or not the show has been canceled. And, what happened on the last episode of the season? I missed it. Was Allison exposed as the Medium?