Was this the right thing to do?

Last Saturday I found out that my boyfriend was drinking with a friend and 2 other girls. I wouldn't have cared as much if he would have told me but he slapped one of the girls *** and than the next day his friend and the 2 girls were saying that my boyfriend slept with her but he claims that he didn't. I would of believed him but things have happened in the past. I really love him with all my heart but today I broke up with him. My heart is broken we have been together a year and all he can say is ok I just need some advice outside of my family. Can someone help me with an idea of what I should do..should we stay broken up or should I give him a chance to make it up to me?