It is not about right and wrong. It is simply this fact that no one can leave a child behind and get remarried to someone so easily. And if they do it there is generally a great degree of internal turmoil and psychological suffering. I doubt if he will ever separate. In fact his unhappiness will find separate routes even later on. How can you expect him to provide you secure and stable marriage when he could not do it with his child. He either does not know what he wants or else he is simply playing games. By now you should understand all this and simply move on.
Affectionately,
Alok Da
