How to make my JsonFormat not error with JsonCPP when I write to a json file?

I was building a quizbowl tracker to keep track of different facts and definitions but my JSON formatting is not working well. When I tried it, the json file throws an error, and I do not know how to fix it. So, does anyone know how to fix this probolem?

So I want my json file to look like this

{
    "sasa": "sasa\n",
    "lol": "saasasa",
    "smth" :  "lolqsas"
}

but it does this...

{
}{
    "sasa" : "sasa\n"
}

and says only one top-level item is for JSON so how do I rechange it to look like how I want it to?

heres my code

#include <iostream>
#include<fstream>
#include<string>
#include<json/writer.h>
#include <json/json.h>

using std::cout;
using std::cin;
using std::string;

class quiz_bowl
{
public:
    quiz_bowl() 
    {
        cout << "Quizbowl facts and stuff\n";
    }

    static void qb_file_add(std::ofstream& qb_file)
    {

        Json::Value event;
        string term, fact, multifacts;
        cout << "what term" << std::endl;
        cin.ignore();
        std::getline(cin, term);
        cout << "what are the facts?" << std::endl;
        int counter = 0;
        while (std::getline(cin, fact) && !fact.empty())
        {
            if (fact == "stop" && counter != 0)
                break;
            else if (fact == "stop" && counter == 0)
                cout << "Do not stop in the first line\n";
            multifacts += fact + '\n';
            counter++;
        }
        event[term] = multifacts;

        qb_file << event;
        cout << "The term " << term << " has been added\n";
    }


};



int main()
{
    cout << "say add to add something or view to view something\n";
    string answer;
    cin >> answer;
    std::ofstream quiz_bowl_file("qb_facts.json", std::ios::app);

    if (answer == "view")
        cout << "viewing\n";
    else if (answer == "add")
        quiz_bowl::qb_file_add(quiz_bowl_file);
    else
        cout << "Invalid argument passed\n";

}

So how would I make the format work with the JSON file and not error by saying that top item message