You closed on January 31st, you either have stock belonging to them or you have sold it at a profit, return the unused stock, make an offer on the remaining sums owing, they are also a small business operating on thin margins I'm sure, you worked with them on trust for the past 25 years and finally stiffed them, not nice, did you order goods from them knowing you were considering closing.
Offering 5k on a 7k debt is not honouring your debt, you said you intended to honour your debts.