Ok, I just checked and this will work. instead of adding your email, add row[2] as the recipient if the emails are in column C. If they are in column D add row[3] and so on.

You can even add more than 1 recipient so if you want to send it to yourself as well as the email in the spreadsheet you could copy and paste and do something like below:

MailApp.sendEmail(row[2], subject, message);

MailApp.sendEmail(youremail@email.com, subject, message);