Will she still get the proceeds from his life insurance? And if not, will me and his three other children get it?
A life insurance contract is separate from an estate. The beneficiary is the recipient of the death benefit from a life insurance policy when the insured person dies. The life insurance contract is completely separate from the state of a deceased person and has nothing to do with the estate.
If you have any questions about how the life insurance proceeds are paid out you can speak with an attorney, financial planner, or the person handling your father's estate to verify if the life insurance is any part of his estate, which I believe it is not.
If you are not listed as a beneficiary, you would not receive any money from your father's life insurance, as long as the stated beneficiary is alive.