Apology accepted. In a perfect world, when a friend tells you they're truly sorry for something they've done to hurt you, step one is to appropriately acknowledge the mea culpa; step two is to formally accept it; and step three would be for you to let the whole thing go. But, newsflash: We do not live in a perfect world. And friendships aren't always so cut and dried.
When a friend apologizes for a transgression—whether right away or eons after the dust has settled—you may still need more time to forgive and forget, especially if said friend has done something, ahem, unforgivable. (Which, BTW, is relative.) But although denying, or putting off, your acceptance just to make them suffer may pale in comparison to what they've done to you, it just isn't the kind thing to do.
Here's how to accept a friend's apology—the right way—so you can release those negative feelings you're holding onto.
Step Toward Forgiveness
If you receive a proper apology, like 'I'm sorry for doing XYZ,' and not a so-called "non-apology" (aka the classic, 'I'm sorry you feel that way'), then take the first step toward forgiveness via acceptance. Make no mistake: You may still be hurting. But making that conscious decision to forgive will always precede that sense of utter exoneration. So, it's completely natural not to be quite "over" it when you choose to say, 'I accept your apology.' Trust that the very act of choosing to forgive will incite feelgood vibes, and genuine feelings of forgiveness will come soon after.
How you accept a friend's apology matters as well. Just as it's super-important for you to be able to tell that she's really sorry, you, too, must mean what you say. True forgiveness means you've thought things through, you acknowledge the gaffe, you're now willing to shake hands, and you agree to play your part in repairing the friendship. And no backsies, either: Once you accept the apology, you're essentially putting the issue to bed once and for all.
A good way to express this is to say something like:
"We all make mistakes. I accept your apology."
"After thinking it through, I realize this was just a misunderstanding and that you didn't mean to hurt me. I accept your apology."
Apologies are also a two-way street: When a friend sees how you were able to so graciously move on, she'll likely remember it. And hopefully, it will have rubbed off by the time it's your turn next to say sorry.
When You Need More Time
It's natural to want to exact revenge on someone who has done you dirty—but doing so only perpetuates, and perhaps magnifies, the issue at hand. (And science has shown that holding onto undue hostility and anger has negative heatlh repercussions.) Instead, take a step back to consider the consequences of an unaccepted apology. The best-case scenario is that your friend gives you all the time you need, no matter how long, to mull it over. But worse yet is the possibility that they'll pull away because they think you'll never forgive, thus damaging the friendship further to the point that it's irreparably broken.
If the friendship is still important to you and you want to salvage it but simply need more time, consider saying:
"I appreciate your apology and I accept it. It means a lot to me. I'm not quite ready to forgive, but I want to be, so I hope you'll be patient with me."
Sure, you may still be smarting from the initial misstep while trying to work through your feelings, but (although it's tempting) try not to keep resurrecting the argument. Likewise, don't insist that your friend's apology wasn't good enough (when deep down you know it was), don't make her apologize over and over, and try not to hold it against her. No one likes or wants to be constantly reminded of the times they've screwed up. Instead, show some compassion, and remember that our mistakes aren't the things that should define us.