I dont even know what to title this...

.. so ive been under a fuck ton of stress lately and it diesnt help me and my boyfriend have been fighting non stop ... well last friday he was being distant and he was acting weird well he was kimda hiding his phone under the table and I get up and come back and I look down at his phone and see that hes texting another girl named Danielle he swears up and down its not true well we broke up bc of it then we got back together and today I was talking to him and he completly ignores me and goes to talk to spencer a guy well his best friend is Danielle shes a slut and he left me to go talk to them and I freaked out .. I did somwthing stupid and made a mistake ... I cut myself and now I just wanna die I feel stupid ... it doesn't help bc at home nobody loved me and im not over reacting the only thing im good for is cleaning babysitting and thats it my grandma tells me im worthless and a whole bunch of other shit ...thats and other story...what do I do... I mean im only 15 and yea.... so what do I do