Hello new:
As you've learned, there's NOTHING you can do, except grin and bear it. But, I thought I read where this is an "investment" for you, and now I see that you're willing to walk away. That might be the best solution. I wouldn't keep an investment that's (1) worth LESS than I paid, and (2) my partner isn't paying her half, but WILL get HALF of everything I make, if I ever make anything.
Maybe I should rephrase what I said above. It may NOT be the BEST thing for you to do, but it certainly might be the best thing for your ex girlfriend to THINK you're going to do. Of course, she'll be sued along with you, and her credit will be ruined too. Maybe the threat of THAT happening might bring her to her senses.
Or it might not.
excon