he hurt me and i can't tell him

so my boyfriend and i got in a big fight and my bestfriend(a guy) knew something was up and texted him threatening to come up to where he lives. i had no idea that he did that and so my boyfriend got pissed because he thought i sent my bestfriend on him and he didn't believe when i said i didn't and he said i've never been so hurt by you in one night. he said he wanted to break up and at this point i had been apologizing since the beginning of the argument, he said that if i would be better and if i wanted to work it out then he would too. the next day i was trying to make things better because his bestfriend(Zach) liked me before my boyfriend(casey) got me. zach got pissed when me and casey started dating and hasn't talked to casey ever since and always gives him the cold shoulder. i texted zach and told him to be mad at me if he wants to be mad but don't be mad at Casey because he misses your friendship. Zach told casey and casey was livid he said that i lost his trust because i told zach something that casey had told me in confidence and that i went behind his back. i didn't mean to go behind his back and i didn't mean to make anything worse, i just wanted to fix something for once and now Casey and i are still dating but he won't even say i love you. i know i hurt him and i have apologized profusely for it and it was never my intention to hurt him but he doesn't see that. i want to tell him that he's not the only one that's hurting right now but i don't want him to think i'm selfish and break up with me. i love him more than words can express and i just want to be good enough for his love. please help.