Co-founder wants to leave, do I pay him back the money he invested?

my co-founder and I have been working on a business idea, where we both invested money into getting it to a MVP stage, it hasn't been launched and does not any money. It is basically a modified wordpress site with no IP. Costs consisted of hiring developers and paying server costs. Since i had 60% equity, I therefore payed 60% of the total costs and he payed 40%. Also worth noting, he still owes money (<$400) for some unpaid costs.

Since he now wants to leave, should I pay him back all the costs he put into the business? (we have no contract/agreement stating our equity split)