If somebody has repeatedly wronged me (in the same way) in the past, am I obligated to keep forgiving him if he asks? On the one hand, maybe this time he finally is really doing teshuva; on the other hand, there's a track record. What happens if I decline?
I'm not asking for a ruling, of course, but rather sources that should inform the decision.
Check the prayers found in most Machzors before Kol Nidrei; here it is from this one (conjugated in the plural, but I'm used to seeing it in the singular; emphasis added):
I hereby absolutely forgive anyone who has harmed me, other than money I can still claim by law, or those who harm me figuring that I'll forgive them. Other than those, I completely forgive, and may no person be punished because of me.
Yoma 87 explains how to properly ask for forgiveness. The offender must go with three friends to the offended, and publicly ask for forgiveness.
If the offended does not want to grant forgiveness, this process is repeated a second, and if needed, a third time.
After the third time, the offender need not ask for forgiveness again - and the offended has transgressed the prohibition of holding a grudge!
So - if the person who is repeatedly transgressing against you isn't admitting his sin in front of friends and asking you for forgiveness, you don't have to forgive him. If this person is not well versed in Gemara, explain that this public admission and sincere request for forgiveness is what you need in order to forgive, and nothing less.
(If the person is willing to shame him/herself publicly by admitting the trangression and publicly asking in a contrite way for forgiveness, that's a fairly decent indication that the person really regrets his/her actions).
This piece from Derekh Eretz Rabbaiti is one of my favorites: There is no reason to treat people unkindly but we don't have to open ourselves up to being hurt. For people who repeatedly cause us pain or transgress against us, I try to remind myself of this. Suspect them, protect yourself, but never embarrass, humiliate, or refuse to show respect to them. The story is awesome!
לעולם יהיו כל בני אדם חשובין לפניך כלסטים והוי מכבדן כרבן גמליאל, ומעשה ברבי יהושע שהשכים אצלו אדם ונתן לו אכילה ושתיה והעלהו לגג לשכב, ונטל סולם מתחתיו, מה עשה אותו האיש, עמד בחצי הלילה ונטל את הכלים וכרכן בטליתו – וכיון שביקש לירד נפל מן הגג ונשברה מפרקתו, לשחרית השכים רבי יהושע ובא מצאו כשהוא נופל, אמר לו ריקה כך עושין בני אדם שכמותך, אמר לו רבי, לא הייתי יודע שנטלת את הסולם מתחתי, אמר לו ריקה אי אתה יודע שמאמש היינו זהירין בך. מכאן א"ר יהושע לעולם יהיו כל בני אדם בעיניך כלסטים והוי מכבדן כר"ג
Every person should always be to you like thieves (marauders) and you should show them respect (honor) like we do to Raban Gamliel. It once happened to Rebbi Yehoshuah that he fed and gave drink to a visitor to his home and helped the visitor up to the loft to sleep, Rebbi Yehoshua removed the ladder from beneath him (the visitor). What did that man do? He stood in the middle of the night and collected all of Rebbi Yehoshuah's things and hid them in his cloak, when the man started to come down from the loft he fell and broke his back, in the morning Rebbi Yehoshua awoke and found the man laying on the floor, he said to the man: Fool! this is what people like you do!? He responded Rebbi! I didn't know that you had removed the ladder! Rebbi Yehoshuah responded: Fool! didn't you realize that we had suspected you from the beginning?!
From here we learn that Every person should always be to you like thieves (marauders) and you should show them respect (honor) like to Raban Gamliel.
Beyond the message, the absurdity of the thief's answer amuses me.
