What should I do?

My husband is in the army. He is over in Iraq for the 3rd time on a 15 mth tour right now. He was only home for 12 months before leaving again this time. When my husband came home after the 2nd one he said the most horribles things to me. Example: he didnt love me anymore, he hated my kids, he would leave me if i ever became fat... I also suspected him having an affair when he was gone. as soon as he came home his cell phone was ringing off the hook, which didnt ring at all while he was gone, and i found 2 secret email address he never told me about. i then started to investgate and found all these phone calls were to a girl and found 2 emails from a girl that basiclly said i love you and miss yada yada yada... My husband to this day denies that this was his girlfriend. he said it was his buddies and he was just the middle man. i wanted so much to beleave him. now today i was just told by another military wife that this girl was my husband girlfriend. so should i stay or get a divor