Is my statement "Allah has wronged me" in a state of sadness considered an act of disbelief (kufr)?

It is not permissible to attribute injustice to Allah Almighty, for He is exalted above it, as He says: "Indeed, Allah does not wrong [even as much as] as an atom's weight." Attributing injustice to Him is a denigration of Him and an act of disbelief. Sincere repentance for this is obligatory.