Forgiveness is the opposite of revenge. It's so important that you can call it a Cosmic Moral Law. (visit my poem on forgiveness)
Forgiveness is a virtue of the Heart; revenge is a negative quality of the mind and emotions in turmoil. Forgiveness is strength; revenge is based on insecurity; fear. Forgiveness comes from the Divine and it's based on unconditional love; revenge is tied up with our baser or gross desires and it's full of conditions and expectations.
Truly speaking, God forgives us daily via His Grace or unconditional Love, or we would most certainly crumple. Again, when we forgive, who is forgiving whom? Without this supreme quality, we cannot clear the resentments or dark shadows from our Hearts, so the devotee is grateful to be given the opportunity to forgive by God Itself, as this helps or facilitates growth. Hope all this is clear to you.
On another matter, I sent you an email today. Have a look.
No, it is not good to associate forgiveness with revenge in this way. You can say, perhaps, that it's a sure way to happiness and a purity-Heart or something along those lines. Much Love, my Brother.