(all deserved credits go to Kevin Spear)
At this very moment, you may be the dumped, or the one who dumped. Or even both. Either which, it could be one of the biggest mistakes of your life, to have had a fated relationship. The dumped is usually not very keen to forgive, forget and move on. They just can't. Forgiving is harder than the rocks from Mars.
Yes, your past may be bitter. But the present you're living should be sweet and better. To successfully move on is to forgive (even unwillingly). It helps to cure the bitterness in your heart. You and me, neither of us is as perfect as any of Allah's Messengers. You may find it's hard at times to forgive, forget, and move on. Well, that just shows you're human anyway. Human with bitterly-torn heart.
Give yourself some time, but you can't have all the time in the world. Afterall, it's not worth to hold grudges and carry it to the afterlife. You can just forgive all the wrongs, the painful wrongs and it's all settled here. The art of forgiving is, never hold grudges.
Remember, anytime is the best time to forgive.