Restrict current user from receiving email using wp_mail

Try this:

//after $wpdb->insert function

$current_user =  wp_get_current_user();
$current_mail = $current_user->user_email;
//$user_email = $member_details->user_email;
if($current_mail !== $_POST['user_email'] ){ // send mail only if different from the current_user email
  $subject = "Congrats! You are added to the Project  -  " . "'" . 
  $project_title . "'";
  $message="If you are not the member of project plz contact us to remove at [email protected]";
  wp_mail( $user_email, $subject, $message );
}