C++ Linked List Deep Copy Constructor and Assignment Overloaded - constructor

Question

#ifndef LIST
#define LIST
#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;
typedef string ElementType;
class List
{
private:
class Node
{
public:
ElementType data;
Node * next;
Node()
:data(ElementType()), next(NULL)
{}
Node(ElementType initData)
:data(initData), next(NULL)
{}
}; // end of Node class
typedef Node * NodePointer;
public:
private:
NodePointer first;
int mySize;
}; // end of List class
This is my overloaded assignment operator, im not sure what im doing wrong, but im beyond frustrated,I've searched the web and read different forums and cannot find a solution to do this, could someone please push me in the right direction, I left out all my public member functions, because none of them operate on my overloaded assignment and copy constructor, I just wanted you guys to get an idea of my layout
overloaded assignment operator
List & List::operator=(const List &rightSide)
{
if(this != &rightSide)
{
this->~List();
}
NodePointer ptr = rightSide.first;
NodePointer cptr = ptr;
while(ptr != NULL)
{
cptr->next = new Node(ptr->data);
cptr = cptr->next;
ptr = ptr->next;
}
return *this;
}
this is my copy constructor
List::List(const List &source)
{
NodePointer ptr = source.first;
NodePointer cptr;
if(ptr == NULL)
{
cerr << "Bad allocation, empty list" << endl;
exit(1);
}
while(ptr != NULL)
{
cptr = new Node(ptr->data);
cptr->next = ptr->next;
ptr = ptr->next;
}
}