MY Lying in, OUR relationship

Hi,
So im a 17 year old boy, provided my age and knowing i have alot to learn, My girl friend and i got into it last night after she found out things ive said wernt true. A little back ground on that, We met nine months ago on the internet and the lying instantly started it seemed. I was suddenly adopted from sweden (one lie) and a bunch more other things. i started this all in about 8th grade when my friends were looking down apon me and just kinda leaving me out. So i came up with these BS stories to make my self more appeaing i guess.. I'm just wondering now, why did i do this for so long and why is it now taking my First real girlfriend almost breaking up with me (im not sure yet she hasnt talked to me since last night) for me to realize that this is an issue that needs to stop.
Many thanks, Nick