dating site while with me

I just found out that my fiancé signed up for a POF (plenty of fish) account while we were in a relationship, 7/23/2014...we started dating 12/13/12 but we were long distance until 2/18/2015 due to him being in the army..what should I do. I found it in his email spam, should I bring it up to him? How am I supposed to marry him, if our relationship is built on lies. I found a girl blocked on his phone, and one blocked on Facebook? We live together, he's at work, I just need advice I guess 😔