my mother and father divorced 7 yrs ago my dad just died do me and my sister have to split the stuff 3 ways with our mother

If your parents were legally divorced at the time of your father's passing, your mother will be entitled to no share of his estate. In the absence of a valid will, the estate of the deceased (all property owned) will pass to his heirs like you and your sister in equal parts. The process is done through the Probate court of your county. Life insurance proceeds to named beneficiaries and jointly held bank account balances need not be Probated, they can pass directly.