How do you handle when someone tries to instill guilt in you?

You should respond with equanimity (upekkha), following the example of monk Sanghamaji in Udana 1.8.

This sutta is about a monk by the name of Sanghamaji, who, when seated under a tree, was visited by his former wife, carrying their infant son. She tried several times to get his attention, and having failed, left the son at his feet and went a short distance away, to observe his reaction. The monk neither reacted, nor said anything to the woman or her child. She then took back the child and left the scene, while lamenting about her former husband's lack of feelings for them, saying "the monk doesn't even care about his son."

The Buddha, who witnessed this supernaturally, praised the monk, saying (I paraphrase here) that he showed equanimity and is free from attachment, and is therefore a brahman.

Previously, I asked a question on equanimity related to this sutta.

Speaking from experience: You will not feel guilty unless you have guilt or sense of obligation within yourself, so it is not the other person's fault; they cannot "make" you feel anything. If you are detached within, you can look on the other with compassion, since they are trying to manipulate you out of some negative emotion of their own. Or you can tell them in a neutral way, "You may be right." If through self-observation you see guilt in yourself, you need to work on that. There is healthy guilt that tells you you are wrong, and there is toxic guilt. Which is it?

I think it's like when someone tries to instil shame in you by insulting you -- i.e. don't accept it, don't participate. (Akkosa Sutta)

Or it's like when someone tries to tell you what the truth is, what the Dhamma is, like the The Four Great References ...

In such a case, bhikkhus, the declaration of such a bhikkhu is neither to be received with approval nor with scorn. Without approval and without scorn, but carefully studying the sentences word by word

... i.e. try to determine whether it's true, whether what's said agrees with what you learned elsewhere. It may be that the criticism is well-deserved and worth paying heed to -- or maybe not, it depends, I can't tell from the question.

Someone saying "I am a victim, you are a perpetrator" might be an unreliable witness.

Some people are like that -- i.e. they blame others!

But the ability to feel shame and remorse is maybe a good thing, and lacking the ability to feel shame -- e.g. Āhrīkya -- not good.

4. Then the Exalted One, realizing the turn their discussion had taken, entered the pavilion, sat down on the prepared seat, and addressed the bhikkhus: "What kind of discussion were you holding just now, bhikkhus? What was the subject of your conversation?"

The bhikkhus replied: "When dawn had broken, Lord, after rising we assembled in the pavilion. As we sat here, the following conversation sprang up among us: 'It is wonderful and marvellous friends, how the Exalted One, he who knows and sees, the Worthy One, the perfectly enlightened Buddha, has so thoroughly penetrated the diversity in the dispositions of beings. For this wanderer Suppiya spoke in many ways in dispraise of the Buddha, the Dhamma, and the Sangha, while his own pupil, the youth Brahmadatta, spoke in many ways in their praise. These two, teacher and pupil, followed closely behind the Exalted One and the company of bhikkhus, making assertions in direct contradiction to each other.' This, Lord, was the conversation we were having when the Exalted One arrived."

5. "If, bhikkhus, others speak in dispraise of me, or in dispraise of the Dhamma, or in dispraise of the Sangha, you should not give way to resentment, displeasure, or animosity against them in your heart. For if you were to become angry or upset in such a situation, you would only be creating an obstacle for yourselves. If you were to become angry or upset when others speak in dispraise of us, would you be able to recognize whether their statements are rightly or wrongly spoken?"

"Certainly not, Lord."

"If, bhikkhus, others speak in dispraise of me, or in dispraise of the Dhamma, or in dispraise of the Sangha, you should unravel what is false and point it out as false, saying: 'For such and such a reason this is false, this is untrue, there is no such thing in us, this is not found among us.'

6. "And if, bhikkhus, others speak in praise of me, or in praise of the Dhamma, or in praise of the Sangha, you should not give way to jubilation, joy, and exultation in your heart. For if you were to become jubilant, joyful, and exultant in such a situation, you would only be creating an obstacle for yourselves. If others speak in praise of me, or in praise of the Dhamma, or in praise of the Sangha, you should acknowledge what is fact as fact, saying: 'For such and such a reason this is a fact, this is true, there is such a thing in us, this is found among us.'

Brahmajala sutta

There is what people say, and how people say it. Concentrate on whether what they say is accurate or not, and act accordingly.

Past and present experience only offers two choices - suffering or learning. Guilt is mostly not useful in that it clouds a reasoned analysis of what the issue is - it embraces suffering over learning. Those that have learnt from their errors, don't feel guilty for their errors, as they have gotten all they can from them, and laid them aside.

If someone still demands guilt from you when you have already learnt your lesson, they likely need to learn that suffering is not permanent.

Householders,

may Venerable fellows, in front and behind, have the compassion for many to possible correct failures and also fill up graps if traced here.

After having put away foolish thought of believing that equanimity is the highest, even supportive, in such cases:

The first one may do in such a situation, when one gets touched unpleased, better feels that way, is to remind on the very importand Dhammapada stanza, that nobody is of more support as someone pointing out ones failure and in the case of even a wise person, one should stick and hold on such a person.

The second thought is possible given to remind oneself that there are actually very less how would tell one a fault, having other interests in the back and that it is also not so general possible to get the chance of a possible very releasing way for a even personal pardon of a transgression.

Being urged by those reminders one should take all his effort and capacity to reconstruct the case, piece by piece, and most importand, with sacca, ujju!, to get not cheated by ones defilement and miss a great opportunity. Possible ask an admirable friend to help in strong cross-questioning.

If, after real trought-full investigation, it is clear that it's either a missunderstood situation, a unlucky and not right blame, or what ever away from what was fact (done), one does not need to take the given and it will stay his/her's, or as a teacher here once told (a little to quick, on fb), "If someone calls you an ox, look if it is like that, inspecting your back" (retold in it's message, not sure if able to find the original, having been banned because of lifting certain critic on another "lost in short cuts").

The many proper approaches further and for each case, would require all detail case by case actions according the whole circumstances. But as already told by the Sublime Buddha to his son, good to clear such cases with an admirable (dhammika) friend/teacher/guide and it might be that the "insulter" actually is the proper one.

[Note: This here is not given for any worldly exchange, trade, stackes, commercial use, dirct or indirect, and may be needed to be deleted if the circumstances do not allow such gifts.]

The important thing to do is to have in mind that these people are puthujjanas, so they are bound to be awful, especially when they think something bad is happening to them. now the puthujjana who receives this ''attack'' better have equanimity.

If this happens too much, then the solution is to no longer live around people who try to make you feel sad. It is hard, especially when it is people in the family, but separating yourself from bad puthujjanas in order to live with the meritorious puthujjanas and non-puthujjanas who train for the noble path is the way to have sati, and ultimately to be awaken, like the buddha tells Ananda in the Upaddha Sutta.

For the ''sutta reference'' you can read the Akkosa Sutta where the buddha is insulted by some puthujjana and the buddha replies that he does not take up the insults.