How can I frogive him? Is there a way to make it better?

Hey guys...I am not here for sympathy I'm here for advice and support because I dont think I cant handle this much longer...I have been with my boyfriend for 4 years.(since I was 15 years old).he was my first kiss.I lost my virginity to him.I have always been moody towards him and hes stuck by me no matter what untill he started talking to someone else because of my lack of suport...he admited it was the bigest mistake of his life.It was a online relationship lasting about a month.after that I felt he was always gaming couldent get his attention and we didnt feel like a couple anymore so I met someone at a party and ended up kissing him because he listend to all mh probably and made me feel safe and secure like i hadnt felt in a while.I did leave my boyfriend before I kissed him but the next morning my "new boyfriend" went back to his ex and I was cruched....my boyfriend of 4 years was there despite his hurt he was there for me.Well recently I have been taking all of my anger and frustration out on him verbally and I didnt realize it ide get upset says "i cant do this anymore" and hell talk to me calm me down and we would be fine after that...well I said that and he wasnt there for me...I took him 4 hours away to pick up his car and I didnt want to hold his hand or kiss him because I stay upset and scared hes going to chest again the next day he took off to alabama wothout telling me and later that day told me he went to see someone and they kissed and that she deserves his loyalty now and it absolutely broke me.I couldent sleep breath every inch of my body hurt and I never realized it would be that painful to see him move on and I understand ehy he did it he said I can come over tomorrow and talk to him but I dont know if ill ever be able to be okay after he kissed another girl.I didnt know it could ever be that painful.I don't know how long they were talking either...Is it worth goingnover there and talking and trying to get better and froget our past or should I let him move on...this made me realize so so much and what ge really means to me and I can't do this without him...