Unstoppable

Unfortunately I've been self harming since the start of this year. I started on my sister's birthday, to be precise, and it was only little at first. I started on my thighs, and I liked the pain because it made me forget. I tried it once on my wrist to see how it felt, and ended up doing it again. But I had to stop on my wrists because summer is coming which means I can't hide under long sleeves. Though sometimes I do reopen the cuts. Then I started on my stomach. I think this hurts the most but it was the best one that distracted me. But now I can't seem to stop. I can't be clean for more that 3 days without feeling the need to do it again, and I really want to stop for the sake of my family and my friends and my mental health. How do I stop?