The Curse of Stalked Prey will not save your Reckless Waif.
Because the evaluation of what zone a creature belongs in (has it been dealt lethal damage, does it have zero toughness, etc.) is a state-based action, it occurs before a player would next receive priority. A player would next receive priority at the end of the combat damage step, which is when the triggered ability of Curse of the Stalked Prey goes on the stack. See the following from the comp. rules:
704.3. Whenever a player would get priority (see rule 116, "Timing and Priority"), the game checks for any of the listed conditions for state-based actions, then performs all applicable state-based actions simultaneously as a single event. If any state-based actions are performed as a result of a check, the check is repeated; otherwise all triggered abilities that are waiting to be put on the stack are put on the stack, then the check is repeated. Once no more state-based actions have been performed as the result of a check and no triggered abilities are waiting to be put on the stack, the appropriate player gets priority. This process also occurs during the cleanup step (see rule 514), except that if no state-based actions are performed as the result of the step's first check and no triggered abilities are waiting to be put on the stack, then no player gets priority and the step ends.
704.5g If a creature has toughness greater than 0, and the total damage marked on it is greater than or equal to its toughness, that creature has been dealt lethal damage and is destroyed. Regeneration can replace this event.
Thus, your creature will go to the graveyard, then the triggered ability that's on the stack will fizzle.