If your share in the money that you both had and in the goods for sale in the shop reached the Nisab (the minimum amount on which Zakah is due) and they remained in your possession for a lunar year, then Zakah was due to be paid even though you were in debt to an amount equivalent to your share at that time.
This is because being in debt does not exempt you from paying Zakah, according to the preponderant opinion of scholars. (Part No. 9; Page No. 356) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.