Sorry man but it looks like she is not telling you the "Whole Truth" something else is up other then her dying gradma.
I agree 100%.
I'm guessing when you moved in with her, you were thinking that you were starting a family. However, she no longer considers you "family" if she is planning (or even thinking of) moving out and away from you. You are no longer a priority in her life.
Now, since you ARE living with her, you need to create a plan of action, or you're going to be stuck with all the bills (unless you can afford to live in your current location on your own). I know you're feeling like 5hit right now, but you NEED to look after yourself. She doesn't give a damn about your situation, she only cares about her own. You need to take charge of this situation, and do what's right for YOU.
If you can't afford to live where you currently are, I suggest you begin looking for a new place ASAP. She moved in with you and got your hopes up for a future together. Now, she's fvcked that up for you. You're now the only one who can take care of your needs and situation. You need to be strong.