Sales manager's request

The owner of the company (a small business) was owed a quarter of a million dollars by a customer and payment looked doubtful. After months of negotiations, stalling and delay, payments on the outstanding balance were made and the customer debt was satisfied. The debt was a result of accepting orders for imported products and the customer placed several orders while product was on the water. Additionally, the customer failed to comply with payment terms that were agreed to. The customer also failed to pay other vendors, and eventually filed for bankruptcy about a year later.
After that experience, the company implemented a pre payment policy for container loads of product ordered by customers of this market segment. This market segment has had several companies fail and file for bankruptcy.
A customer who had agreed to the prepayment terms and had ordered prepaid containers has stopped ordering and when questioned why, replied that they received more favorable terms elsewhere.
I (the sales manager) would like to continue to service this customer and market segment by starting a separate company on my own, while still continuing in my current position with my current employer, by offering more favorable terms to this customer and others in this market segment. Would it be ethical to do so??