Are you thinking of "malice"? Maybe "animosity"? Or "loathing"?
Resentment.
The word disgruntled means dissatisfied, discontented, or upset, and is notably used for a disgruntled ex-employee, to mean someone who feels misused and may still harbor ill will against a previous employer.
The noun "animosity" means ill feelings or dislike.
The noun 'bitterness' is an abstract noun as a word for a feeling of deep anger and ill-will; a feeling of resentment; a word for an emotion.The noun 'bitterness' is a concrete noun as a word for a harsh, unpleasant taste.
A feeling of deep and bitter anger and ill-will
It is to 'ail'
ill will or bitter resentment, hatred rancor is a noun
Grudgingly
That is not a word. The actual word would be unsuitable. It means inappropriate.
You are full of Malice wishes. Malice means ill will.
If that could be "i," the answer is "ill."
Rancorous means resentful or bearing ill-will, generally negative feelings directed towards a specific person or thing.