I told my ex boyfriend that I cut myself and!!?

So like I said I told my ex boyfriend that I Been cutting myself,now the only reason why i told him is cause i felt he was the only one i could tell my secret 2 since we still love each other and we still talk like everyday and I also read online that it's good to tell someone that you cut your self so it can help cause I'm tryin to stop cause my whole family is starting to find out cause since Im starting to wear shorts and my scars are showin an I hate being asked "what happen to your legs" and so on and 2day me and my ex bf were talkin on the phone and we kinda got into a lil argumeant an then he started saying I wouldn't like to be alone with you in a room cause you might cut me and he started calling me stupid for cutting myself and just making jokes outta it, I jut started cryin I guess I went to the wrong person with my secret, so anyways I'm sorry for this long question but how do I stop cutting myself and what should I tell my ex boyfriend for how he hurt me for joking about my secret Like that? Pls don't answer if your gonna be rude k? Thnx & oh I'm 17 & my ex bf is 19 if anybody wants 2 knw