unforgiving

adjectives

unwilling or unable to forgive or show mercy
"a surly unforgiving old woman"
unforgiving
antonym
forgiving
is similar to
disposed to seek revenge or intended for revenge
"more vindictive than jealous love"- Shakespeare; "punishments...essentially vindictive in their nature"- M.R.Cohen
revengeful, vengeful, vindictive
not to be placated or appeased or moved by entreaty
"grim determination"; "grim necessity"; "Russia's final hour, it seemed, approached with inexorable certainty"; "relentless persecution"; "the stern demands of parenthood"
grim, inexorable, relentless, stern, unappeasable, unforgiving, unrelenting