Datagridview and checkbox open new form

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C#

In Form1 i add DataGridView and it contents 10 rows. and column[5] is CheckBox, and this CheckBox is ReadOnly.
Now i want to do that:
when double click on Row1 the Form2 open and Checkbox checked, and when close Form2 the Checkbox unchecked, ect.

What I have tried:

I tried this, but i can't tried foreach in Frm_Closing:

private void datagridview1_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
{
    Form2 form = new Form2();
    if (datagridview1.CurrentRow.Cells[5].Value == null)
    {
        datagridview1.CurrentRow.Cells[5].Value = true;
        form.MdiParent = this.MdiParent;
        form.Show();
        form.Closing += Frm_Closing;
    }
    else
    {
        form.Activate();
        form.BringToFront();
    }
}