Need helpp? This girl that I likes likes me back but there is a big problemm!?

Ok so almost 2 weeks ago I told this girl I like her. Later that day she told me she likes me back, I was happy:)! But then something came up. I knew this girl for a year now and we gave been kinda friends and then I told her I liked he blah blah blah but there is one problem. Her last relationship didn't go to well and she didn't want to go out with me bc she was afraid that she wouldn't be a good gf and wouldn't be able to Handel a relationship. So she fake went out with this other guy just to see if she can Handel a relationship.yeah great idea except we like eachother now and she has a bf:(! I think she can Handel a relationship now but she wouldn't brake up with the guy(I dont know why) We say we love eachother but then againshe has a bf! Please help!