a really rough break up:: please help me!!

i was having trouble breaking up with my boyfriend. we had been dating for three months and i really liked him. there were some problems in the relationship that led me to want to break up with him. i asked my “friend” for advice one school day and behind my back she told him these things. he decided to snapchat me and say “hey. so. do you wanna break up” then instead of waiting for my response he blocked me in any way possible, including snapchat, messages, and both of my instagram accounts. he has been talking bad about me since then and called me a bitch, but he hasn’t yet faced me or said anything to me, remember it’s only been a day. that same girl that told him i wanted to break up with him, is trying to get with him. i found out that while we were dating she sent him pictures in her bra and would rub his leg (the upper thigh). this is all extremely upsetting to me because he’s going around saying he could do better and some of his friends are agreeing. i would be heartbroken if i wasn’t going to break up with him in the first place, but even though he treated me like shit after the break up and said all these mean things i can’t help but go back and read our messages and think about the good times. for some reason an part of my heart really misses him, and the other half tells me he doesn’t deserve my tears and that i’m too good for him. i try so hard to be confident at school but it’s so hard when a little pet of me misses him. how do i get rid of this feeling? my brain knows he doesn’t deserve my tears and my breath but my heart doesn’t want to let go.