Since my Partner's parents are broke bitches, I'd be very suspicious of where they got said money and why they're offering it to me when they have so much debt to pay off...
The simple answer to this question is: No, I would never permanently leave my partner for any amount of money or worldly possessions. I might, however, be tempted to try and trick them into thinking we had separated, and then taking the money and my honey and making off to a far away island where they'd never find us. ;D Or, conversely, we could stage an elaborate mission to track and steal said money. I totally wouldn't mind taking from my Partner's Parents, given all that they've taken from us, and how much they seem to despise me.
In the end, if all else failed and I had NO way of obtaining the money without leaving my partner for good, I'd pass it up. All the money in the world is worthless if you can't be with the person you love. Besides, who would I shower with gifts and affection then? *Pouts*