Am i being selfish about this?

No, it is unlikely that your dad would have to help her pay it off. I live in a marital property state, when my husband and I divorced, I had to buy him out of his share of the equity in our home. I had to refinance the mortgage in my name only; I included the money that I owed him in the refinance. If I could not have gotten the loan; we would have to sell the house and divide the equity.