Please help me stop cutting?

please help me stop cutting i dont know how to stop it makes me feel better and i've tried to stop but when ever something of panic happens i freak out and instead of talking about it and letting it out i grab a really sharp knife or blade and slit my wrists so much they dnt stop bleeding for hours. ive tried rubber bands but i just end up slapping them so hard that i get these large welts on my wrists and usually end up bleeding, and i already keep a journal but it doesnt seem to work someone please help me i feel worthless all the time and can not stop my self from self inflicted pain.