i poisoned my best friend and lost her

My best friend and I have been best friends for years like 7 years. And she always thought i was cool and she put pressure on herself. I didn’t know. She was only 13, when i met the boy (last two posts) and she was literally a child and she drowned in my problems. I didn’t know because she never told me or when she did i wouldn’t listen. I miss her so much it feels like a heartbreak