To the OP: I’d struggle with the deceit myself, but only you can decide on that one. I was screwed over by a gf many years ago and the truth was a lot more than she first admitted to…
I’d get professional advice, both on your marriage and on the finances. If she racked up the debt I would have thought it’s only fair for her to sort it out (esp if she has her own source of income from the business) so not sure of the rationale for it to be loaded onto the (shared) mortgage.
Good luck…