"am I protected against negative feedback, no matter how it will end."
NO.
eBay will protect you and remove negative feedback given as a result of you filing a complaint for non-payment if the buyer has not paid.
However, if the buyer pays and later leaves negative feedback for any reason other than your original complaint, then the negative feedback will stay. For example: if the buyer receives the item and feels the quality is not acceptable, a negative feedback will not be removed by eBay; same thing if the buyer pays and files a negative feedback at a later date for non receipt of the goods or very slow shipment or poor packaging or... whatever..
