You are assuming - big assumption - that the product is not the problem, but a 100% churn rate for 50-60 users makes me suspicious about the product itself.

Then, right off the bat, you have started blaming your co-founder for a failed product launch. This is no good.

Submit a "Show HN:" post with your product, let´s see what you have got and let´s see how HN community can help.