'For my own sake I must forgive you.
One cannot always keep an adder in ones breast to feed on one
nor rise up every night to sow thorns in the garden of ones soul.'
(Oscar Wilde cited by Hughes in Forgiveness in Victorian Literature: Grammar, Narrative, and Community, 2015, p149).
Bitterness will poison me slowly and destroy my soul, so forgiveness will save me according to Wilde.
Hughes (2015) talks about the therapeutic value of forgiveness and likens resentment to a poison or toxin, citing Anne Lamott's suggestion that: 'not forgiving is like drinking rat poison and waiting for the rat to die' (p.134 cited in p.149, 2015).