If you insult someone, Krsna will arrange for you to be insulted too. You can't clap your hands with one hand. In other words, you have done bad things in the past and therefore the corresponding reactions come in the present.
If you are offended, you do not need to do the same in response. Even if someone is going to poison you, don't get angry. One should be like Sri Prahlada Maharaja and Srila Haridas Thakura. Although Haridas Thakura was beaten in many market squares, he prayed, " O Krishna, be kind and forgive them. These beatings are the result of my past sinful activities, and thus Your mercy is manifested." Keep calm and chant, " Hare Krishna Hare Krishna Krishna Krishna Hare Hare Hare Rama Hare Rama Rama Rama Hare Hare."
Think like this: "I'm completely worthless. I have offended many Vaishnavas and as a result I have become so stupid and good for nothing. Although I chant the holy name, tears do not flow from my eyes and my heart does not melt. O Krsna, what should I do?" You should also remember Sri Caitanya Mahaprabhu and pray, " O Caitanya Mahaprabhu, You are bestowing causeless mercy. Please pour Your mercy on me. In this Kali-yuga, life is very short, full of problems, and the mind is too restless. What should I do?
Problems beset me every time I try to practice bhakti. I have no association with Vaisnavas, I am weak, and Krsna does not favor me. O Caitanya Mahaprabhu, I know only You. You have bestowed mercy on Jagai and Madhai. But why not me? I am even more bad than they are, so I need Your favor."
Excerpts from lectures ...
Sri Srimad Bhaktivedanta Narayana Goswami Maharaja