I miss him

Well, my father is a anonymous sperm donor. If you had asked me a year ago how I felt about him, I would have felt mild curiosity and excitement. I wasn’t really concerned about him at all. But now I miss him like crazy. It sounds weird I know, how can you miss someone you never knew? But I feel it all the same. I’m also furious (and I know this sounds bad) at my mother. How dare she willingly deny me the right to know him? And my half brothers and sisters. I’ve tried talking to her about it but she just gets a face like a smashed plate every time in mention it. Sometimes I really hate her.