Executors have a legal duty to follow the provisions of the will precisely as stated and to ensure all divisions and legacies are paid out in compliance with the express wishes of the deceased person.
This is after all legitimate expenses, costs and (IHT if any) have been paid out of the estate proceeds once all the monies have been in-gathered. Any debts owed by the estate have to be proven...just in the same manner as any debts owed to the estate before they should be considered as a legal liability.
The money you each borrowed was on a informal understanding otherwise without written contracts it would be deemed as a gift, therefore not a legitimate or legally enforceable loan. This executor is not correct and could be removed for acting improperly or failing to carry out their duties correctly or held personally liable for any discrepancy. Unless any documentation that stipulated the legal requirements terms and conditions for repayments of the alleged loans were produced, then these sums of money would be deemed as gifts and disregarded from the calculations when distributing the estate.
(except only for IHT purposes if the estate was large enough.. and the donor has died within Seven years of making the gifts)..which by the sounds does not affect your case.