How to handle the background process and ending the process in windows form application

Question

I made a utility in windows form application that reads a text file and performed some business logic and then exported that data to the excel, for excel processing I have used Microsoft Excel XX.X Object Library. I have added following methods that are used to initialize the Excel library objects and then add data to it.

For creating the excel doc :

public void createDoc()
    {
        try
        {
            app = new Excel.Application();
            //app.Visible = true;
            workbook = app.Workbooks.Add(1);
            worksheet = (Excel.Worksheet)workbook.Sheets[1];
        }
        catch (Exception e)
        {
            MessageBox.Show(e.Message);
        }
        finally
        {
        }
    }

for adding data to excel :

 public void addData(int row, int col, string data)
    {
        try
        {
            worksheet.Cells[row, col] = data;
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }

    }

then I have added the following code to run in background :

void backgroundProcess(object sender, DoWorkEventArgs e)
    {
        SpecialCharacter specialCharObj = new SpecialCharacter();
        //creating excel Doc
        CreateExcelDoc excell_app = new CreateExcelDoc();
        //creates the main header
        excell_app.createHeaders();

        string[] readText = File.ReadAllLines(txtAddFile.Text);

        //MsgLabel.Text = "Exporting to excel......";

        foreach (string s in readText)
        {
            specialCharObj.setAllFields(s);
            excell_app.addDataToExcel(specialCharObj,count);
            count++;
            bgw.ReportProgress(count-2);
        }

        excell_app.writeDoc(txtAddFile.Text.ToString()+"_Output.xlsx");

    }

the addDataToExcel calls the addData method of the excel class which adds multiple fields in the excel sheet as follows :

public void addDataToExcel(SpecialCharacter obj,int count)
    {
        this.addData(count, 1, "Debenhams");
        this.addData(count, 2, obj.identifier);
        this.addData(count, 3, obj.date);
        this.addData(count, 4, obj.referenceNo);
        this.addData(count, 5, obj.IdentificationCode);
        this.addData(count, 6, obj.franchiseName);
        this.addData(count, 7, obj.storeNum);
        this.addData(count, 8, obj.InvoiceNum);
        this.addData(count, 9, obj.divisionNum);
     }

now the real issue i am facing is i have a form closing method that process the work at the closure of form in between the processing, the method is written as follows :

private void DebenhamsSpecialCharUtility_FormClosing(object sender, FormClosingEventArgs e)
    {
        if (MsgLabel.Text == "Exported")
        {
            Application.Exit();
        }
        else
        {
            if (e.CloseReason == CloseReason.UserClosing)
            {
                DialogResult result = MessageBox.Show("Do you really want to exit?", "Dialog Title", MessageBoxButtons.YesNo);
                if (result == DialogResult.Yes)
                {
                    //excell_app.excelAppClose();
                    Application.Exit();

                }
                else
                {
                    e.Cancel = true;
                }
            }
            else
            {
                e.Cancel = true;
            }
        }

now what I am required to do is end my excel processing that is running in the background if the user close the form during processing , but if I do that it raise an exception as it is looping through the file and adding data to excel and so it cannot release the Excel object. I have use following code for deallocating excel objects :

workbook.Close(true, misValue, misValue);
app.Quit();
System.Runtime.InteropServices.Marshal.ReleaseComObject(app);

So I need someone to provide me with the solution of ending the process without raising any exception as it is looping through the data and adding the data to excel.