Making others take oaths unnecessarily

Q: I asked someone to say some specific words. That Person said it in normal way but I knew it from my heart that that person was lying to me so I asked him to swear to Allah on this and I insisted many times. During our conversation that person once mentioned that my (that person's) life in this world is destroyed and you want to ruin my Akhira (world hereafter) as well. At last that person said those words with "swear to Allah". My question is now what to do? What is the Kafaarah in this situation and what are the obligations on me towards that specific incident because it was I who was insisting for this again and again. What should I do for that person?