Adding name to a deed

I will start out by telling you the circumstances leading up to this question. My sister and I were on my parents will, meaning the house was left to both of us. About six years ago my husband lost his business, and I told my sister in confidence that I THOUGHT that he owed over fifty thousand dollars in back taxes, (I was in error he owed five thousand), she seemed sympathetic, so when she and my Mother called me aside a few months later and told me that they had taken me off the will, so that the IRS would not take the house as payment, I was hurt beyond belief, I felt so betrayed. Had they come to me and talked, I would have understood the reasoning and more than likely agreed to change, but they did not. That said my Mother died in August and now my sister wants to add me to the house deed. Now I am a little naive I admit it, but I think the reasoning is this. About seven years ago my Mother took out a forty thousand dollar home improvement loan, she paid just the amount so when she died she still owed thirty nine thousand dollars, I am thinking my sister did not take that into account and now that Mom has died, her being the beneficiary of the house, has to assume the loan payments, am I correct? Thank you for taking the time to read this