I wanna help my friend

My friend just sent me a bunch of her sh and it's clear she wants my attention on this topic. I always use to joke abt sh as a coping mechanism and like three days ago we were in the same bus coming back home and she rolled up her sleeve looking at smth on her arm. I joked and said "you're checking for sh cuts?" And she just went and showed me all her arm (which had snth like 20/30 fresh cuts). And I kinda just froze and stared at it with wide eyes, she laughed at my reaction. It's clear that she's trying to get my attention but idk how to help her, I suck at comforting. I just want to hug her and tell her that I love her (as a friend) and always be there for her but I feel so uncomfortable idk why. She also texted me she loves seeing the blood mixing with water when she washes herself. What do I do, I love her so much I don't want her to do this. Consider we're both 14 and I can go to her house kinda whenever I want and we meet everyday at school but we're not in the same class