Someobe confessed to me that they tried self harm and i dont know what to do

A few months ago, I attempted suicide, and he's one of the few people who knows, apart from my parents. Recently, he confided in me that he's also struggled with self-harm, and now I'm at a loss for what to do. I feel like I haven't fully processed why I made that decision, and I’m still unsure of what I’m feeling. He’s one of the few people in my life that I truly care about and love, and I can’t bear to see him going through this. I feel so helpless and useless right now, and I don’t know how to comfort him. I just wish I knew what to do.