pent-up resentment; grudges and hard feelings
「辛み」 has another reading with different meanings.
胸に辛みを抱えて生きた。
She lived with a deep resentment in her heart.
彼女の言葉には辛みが滲んでいた。
Her words were tinged with pent-up resentment.
長年積もった辛みが一気に溢れ出した。
Years of pent-up resentment suddenly came pouring out.