I need Help because I’m self harming

Patient: HelloI have been self harming for 3 year and I know I need to stop I got angry over a petty little things. Like yesterday and I tried to commit suicide even though I know I shouldn’t because someone said something and I took it the wrong way. I ended up on the bathroom floor talking to my dead grandfather who I was really close to but died 3year ago. No one knows I cut and I would like to keep it that way but I’m scared if I do I may end up killing myself. My sister gets angry and takes it out on everyone else but I get angry and cut my self it doesn’t make sense and I really don’t want to die because I’m only 15 and want to live life. Please help.