My life turned a complete 180 within seconds. Please help me..please. I'm so hurt. 

I was in a committed relationship for five years and in arms reach of a wedding then my world came crashing down on me.  I'm thirty and have devoted my love for a man whom I thouht was the man of my dreams.  He treated me with so much respect, admiration, and placed me on a pedastal.  He was loving, caring, and affectionate but behind closed doors, he chatted with woman sometimes innocently while most of the time, sexually.  He was aggressive in his speech with woman during these chatting sessions yet he was so gentle, loving, and passive with me.  I also found some emails of him meeting a lady at an out of state conference and asking her to lunch.  Why would a person who claims to love me so much and has showed me with great passion throw it all away.  Since leaving him, he has called me, emailed me, and visited me nonstop.  He begged for forgiveness and promised it will never happen again.  I don't believe him because I've always felt "Once a cheater, always a cheater".  My heart feels the kind of pain that I never thought existed.  How do I get through this?  What suggestions can I get?  Help me get through my agonizing days alone, lonely, in anguish.  How do I stop crying.  I cry so hard my eyelids swell up similar to an allergic reaction.  Help me please.  Someone help rid this pain for me.....please.