all yours and hers relationship decisions and her jealousies etc are not the fault of the mortgage company though - they will look at what they say you can afford and that'll be that. it's simply black and white to them i'm afraid (as it will be to the courts)
this is a person who by your own account manipulated you into getting a house with her, went out and had loads of fun, left you paying the mortgage by yoursel, and you think she can be trusted?
Anyway, if she has debts, her creditors might well decide to get a charging order on the house as one of her assets