How can I finish a form and its Threads safely?

Question

It is my first question here, so I am a bit lost (And English is not my native language). I am doing a Multhread server, and when I try to stop the TcpListener or to terminate the program with Application.Exit(), I receive the following error:

An unhandled exception of type 'System.ObjectDisposedException' occurred in System.Windows.Forms.dll

Pointing to the line: this.Invoke(d, new object[] { text });. I am not used to work with threads too, so can anyone show me how to close everything safely?

Thank you!

public partial class Form1 : Form
{
    public IPAddress enderecoIP;
    public TcpListener escutar;
    public List<Thread> threads = new List<Thread>();

    public Form1()
    {
        InitializeComponent();
    }

    private string ipp ()
    {
        string localIP;
        using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, 0))
        {
            socket.Connect("10.0.2.4", 65530);
            IPEndPoint endPoint = socket.LocalEndPoint as IPEndPoint;
            localIP = endPoint.Address.ToString();
        }
        return localIP;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        try
        {
            enderecoIP = IPAddress.Parse(ipp());
            escutar = new TcpListener(enderecoIP, 8001);
            escutar.Start();
            textBox1.AppendText("Servidor iniciado no endereco IP " + enderecoIP.ToString() + "\n");

            for (int i = 0; i < 100; i++) // numero maximo de clientes
            {
                Thread newThread = new Thread(new ThreadStart(iniciarServidor));
                newThread.Start();
                this.threads.Add(newThread);
            }
            this.button1.Enabled = false;
        } catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }

    private void iniciarServidor()
    {
           try
           {
                Socket s = escutar.AcceptSocket();

                byte[] b = new byte[1000];
                s.Receive(b);


                System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
                string palavra = enc.GetString(b);
                string linha = "";

                foreach (char c in palavra) {
                    if (c!='*') {
                        linha += c;
                    } else {
                        this.SetText(linha+"\n");
                        linha = "";
                    }
                }

                s.Close();

            }
            catch (Exception e)
            {
            this.SetText(e.Message);
            }
    }

    private void SetText(string text)
    {
        if (this.textBox1.InvokeRequired)
        {   
            SetTextCallback d = new SetTextCallback(SetText);
            this.Invoke(d, new object[] { text });
        }
        else
        {
            this.textBox1.AppendText(text);
        }
    }

    delegate void SetTextCallback(string text);

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        foreach (Thread t in this.threads)
        {
            if (t.IsAlive)
                t.Abort();
        }
        this.escutar.Stop();
        Application.ExitThread();
    }
}