Hey there phightphear,
Really the only thing best for you would be to celebrate your birthday one on one with your friend that wanted to throw you a party and enjoy the day. If he’s a true friend he won’t mind going out to celebrate and help you with your problems. No need to worry about coworkers, etc attending.
Remember nothing special will change at 30, unless you put in the effort and learn that sometimes rejection is protection. Just continue to focus and put your all at work and improve within yourself and you’ll attract another woman that will share those same positive qualities.
Take care