Nasty Breakup

So me and my boyfriend had been together for about 4 months (I know. not a really long time.) but we met and really hit things off. he made me feel like I could be me around him and didn't have to hide. We got along better than I've ever gotten along with anyone. Until I found out he had been lying to me. We tried to work through it and things were great for a while until it happened again. And we decided to work on it again. then about 2 weeks ago, he stopped kissing me and stopped saying I love you and did even really say goodbye when he left so I knew something was wrong. long story short, I gave him the benefit of the doubt and we tried working things out. I found out last night he had been talking to his ex the whole time. So, my heart hurts and I'm angry because I thought he was different. Any coping advice ladies?