Boyfriend trouble need as much help as possible

So me and my boyfriend have been together for 2 years but broke up last year for a couple of months and back together in January. I slept with someone else while we weren't together and I told him as soon as we got back together. He has made me feel so guilty about it! In every argument we have had he says "atleast I didn't sleep with someone else" "you're a slut" "I have only been with you in these 2 years"! Recently the other day I went to a friends birthday party and a girl came up to me and told me that he took her virginity and they dated for a month when we weren't together. He yelled at me for believing her but eventually he owned up because I had proof. I'm really angry that he lied to me about it. And I'm really hurt that he has made me feel so terrible for sleeping with someone else when he did they same thing....should I stay?