Loneliness in my heart

I thought the feeling of loneliness would go away if I spent enough time with others but, it’s still there and it’s eating away at me. I know that people love me but my anger and sadness never seems to subside. Even when I’m with people I feel so cold and alone. How do I find how to be happy and whole again. I put on this smile and pretend to be happy, but what’s it like to really be happy? Cutting only makes me feel better for a few moment and that feels worth it. But it makes everyone around me nervous. I don’t want to lie but when I tell people the truth I think they think I’m crazy and that I’m trying to get attention. I just want it all to end and go away. I don’t even know what taking care of myself means. And when I talk about it, it just hurts more. Why am I so alone?