Should i tell my him im feeling depressed?

Hi, im 14 and lately i have been feeling like crap. i feel really sad and worthless and i just want to die. i have felt like this before and i used to cut to make myself feel better. there has been a period where all of this left me. but now its coming back, i want to start cutting again but i cant. i have a boyfriend who i really love and he begged me never to cut again. i promised i wouldn't but now that promise is becoming harder and harder to keep. should i tell him how i am feeling? he promised me he would love me whatever happened and he would never leave me. i want to tell him but i cant, i don't want him to worry about me anymore than he does already, because i hardly eat anymore and he knows and he is already worried about me because of that. i don't want to give him another reason to worry about me but i want to tell him because i don't like keeping it from him. i feel like i am betraying his trust and its hurting me inside. should i tell him how i am feeling or not?? PLEASE HELP!! i cant take the lying anymore ( when he asks am i okay i always reply yes im fab and crap like that )