I’ve had an obsession for a girl that I’ve never even spoken to before for over a year now, and I can’t get rid of it. What should I do?

She even has a boyfriend now, and I don’t even care. I have tried to stop thinking about her for months now, and I just can’t do it. She is in my thoughts almost 24/7. Lately she even shows up in my dreams.

I don’t know what to do at this point.