There are more important things in life than what car you own! Relax matey.
Call her up and apologise for being a complete **** and say that you are just being stupid cause you are an idiot and no nothing about cars.
Or you can sit on your ass and do nothing and keep feeling like a ****.
Up to you really.
Its your woman ffs.
Get a grip, sort your car buying/money/life out and stop being a green eyed monster.
Be happy for her for christ sakes.