I'm obsessed with someone
That seems extreme. What makes you obsessed with them?
I don't even personally know her.
While love at first sight can be okay, it isn't good when it leads to an unhealthy obsession. Rather than stalk this woman, try asking her out if she's single and available. If she turns you down, you now have a reason for moving on and finding someone else who would be more compatible with you as a romantic partner.
Okay I'll just stalk her with my eyes from afar.
Even if you're not harming her it's still unhealthy for you. You'd be better off moving on or finding someone you can actually be with. Otherwise you're just wasting your time and energy obsessing healthily over someone you can't have.