I know what you're going through, having been there before and I still am, only not as serious anymore. I'm not a psychologist or anything, but what you're describing sounds like limerence. Google search it, there's a lot of info about it on the web. It's basically a debilitating crush that lasts way longer than what an unrequited crush should last (over two to three years, generally) that goes beyond what is considered a healthy neurophysiological reaction to someone we find attractive.

There are people who are "serial limerents," who experience this with different people from adolescence to late adulthood, and it can severely, negatively affect one's life, as one can imagine. It's like a drug addiction in many ways. Even if this is the only time you've experienced limerence, it sounds severe enough to seek therapy. The cause is usually a result of low self-esteem, relationship with parents growing up, and genetics. So while I know how much you're suffering, there is hope.

The most important thing for you right now, I think, is to learn about it, find a GOOD therapist for yourself or at least seek e-help if you still have no insurance, and remind yourself of your good qualities and connect with people around you. One of the biggest reasons many of us become infatuated with celebrities is because we don't have enough healthy, personal relationships, and our brains really need them in order to function well.

There's also something called "Erotomania," but I don't know enough about your experience to say that's what it is. Erotomania is like limerence, only it usually involves relentless fantasies and even delusions about a famous person and their (perceived) relationship to us. You seem to have too much self-awareness for this to be the case, although you may have some symptoms of it. Please don't feel guilty or ashamed about it, what you're experiencing is more common than you think, you're not alone. I'm a serial limerent, but I've improved greatly with help. I hope you're okay, and I hope to hear back from you soon.

Hope and keep busy.