That question comes my way every year around this season. (I've written about this before.) I find that it is asked most often by women, who may face (as women, and as Jews) a double whammy of cultural messages instructing us to be forgiving even at our own expense. But people across the gender spectrum struggle with this question.
Many of us know the teaching from Rambam (in his Hilchot Teshuvah, "Laws of Repentance / Return") that when someone has wronged another person, the one who committed the wrong must make teshuvah and seek forgiveness, and the one who was wronged is obligated to forgive. "Obligated" is a strong word. Is it ever okay, Jewishly, not to forgive?
Short answer: yes. Yes, Jewishly speaking, there are times when it is ok not to extend forgiveness. Longer answer: when the person who wronged you has not made teshuvah (more in a minute abut what that means, and what is implied therein) not only are you not obligated to forgive them, but one could even make the case that granting forgiveness in that circumstance is forbidden. Because if you were to forgive under that circumstance, without their teshuvah, your forgiveness would give cover to the unethical behavior not only of harming you in the first place, but also of choosing not to make teshuvah.
A reminder: teshuvah, which is often translated as "repentance," comes from the root that means turning or turning-around. Teshuvah is the work of turning oneself around, turning oneself in the right direction again, turning over a new leaf, re/turning to God and to the state of righteousness to which we are all expected to aspire. When we miss the mark in our relationship with God, we can make teshuvah and repair the broken relationship. When we miss the mark in our relationships with each other, we can make teshuvah and (maybe) repair the broken relationship. Repair may not be up to us. But our own teshuvah work is.
Here's Rabbi David J. Blumenthal, in his essay Is Forgiveness Necessary?
If the offender has done teshuvah, and is sincere in his or her repentance, the offended person should offer mechilah; that is, the offended person should forgo the debt of the offender, relinquish his or her claim against the offender. This is not a reconciliation of heart or an embracing of the offender; it is simply reaching the conclusion that the offender no longer owes me anything for whatever it was that he or she did. Mechilah is like a pardon granted to a criminal by the modern state. The crime remains; only the debt is forgiven.
The tradition, however, is quite clear that the offended person is not obliged to offer mechilah if the offender is not sincere in his or her repentance and has not taken concrete steps to correct the wrong done...
The principle that mechilah ought to be granted only if deserved is the great Jewish "No" to easy forgiveness. It is core to the Jewish view of forgiveness, just as desisting from sin is core to the Jewish view of repentance. Without good grounds, the offended person should not forgo the indebtedness of the sinner; otherwise, the sinner may never truly repent and evil will be perpetuated. And, conversely, if there are good grounds to waive the debt or relinquish the claim, the offended person is morally bound to do so. This is the great Jewish "Yes" to the possibility of repentance for every sinner.
If the person who wronged you has done teshuvah and is sincere in their repentance, then tradition asks you to forgive. But that's a big 'if.' How can you tell if the person's teshuvah is sincere? My own answer relies on a combination of factors. For starters, the person who wronged you has to actually apologize (and I mean a real apology.) Ideally that apology should feel sincere to you. But the person's subsequent actions are of greater importance. Saying sorry isn't enough: they also have to take concrete steps to correct the wrong, and they have to show with their actions and their choices that they have changed.
One rubric says that we can tell if teshuvah is genuine when the person making teshuvah has the opportunity to commit the same misdeed as before, but this time makes a different choice. (That's Rambam again.) Imagine that I harmed you physically by driving over your foot. I would need to not only apologize to you for hurting you, and do what I could to correct the wrong (giving you an aspirin, or perhaps a pair of steel-toed boots?), but also, the next time I was driving my car near where your foot was resting, I'd need to notice your foot, make a conscious choice not to drive over it, and then follow through with that choice.
But if my apology to you felt insincere -- "Whatever, you're overreacting but I'm sorry you're upset" -- you would be under no obligation to forgive me for the harm. And if I didn't do what I could to make up for having driven over your foot, ditto. And if I didn't take steps to ensure that I never drive over your foot again, ditto all the more. (It's a ridiculous example, I realize. I use it because it lets me illustrate the principle I want to communicate, without getting into the kinds of hypotheticals that might evoke or re-activate the interpersonal traumas that bring people to me with these questions about forgiveness in the first place.)
If someone has harmed you -- whether in body, heart, mind, or spirit -- and they come to you seeking forgiveness, you're allowed to take the time you need to discern 1) whether their apology is genuine, and 2) whether they have done all that they could to remedy the damage, and 3) whether they have done the internal work of becoming a person who would no longer harm you in that same way given the opportunity to do so again. If the answer to any of those questions is no -- and kal v'chomer (all the more so) if they don't apologize in the first place -- then you are not obligated to forgive them for harming you.
Emotionally and spiritually, pay attention to what your heart and soul are saying. If your heart and soul resist the idea of forgiving someone, discern whether that resistance is a case of holding on to an old resentment that you'd be better off releasing -- or whether it's a case of healthy self-protection. If offering forgiveness would serve you, then I support that. But Jewish tradition does not require us to re-inscribe the harm done to us by forgiving our abusers. And as Rabbi Danya Ruttenberg notes in her excellent twitter thread on this, the person who needs to repent can do so whether or not the person they harmed forgives.
G'mar chatimah tovah: may we all be sealed for goodness in the year to come.