It appears that your mother didn't leave the house to you in her will as an absolute gift. The house is part of the residue. It means that you will have to distribute $50,000 of the estate to your brother first, after payment of all debts, and distribute to yourself whatever is left as the residue.
My suggestion is to seek assistance without delay from an estate planning lawyer about your options.
My suggestion is to seek assistance without delay from an estate planning lawyer about your options.