Please listen, I understand so much where you are coming from, and yes he should have a relationship with his dad but you need to keep him at a distance from you that having him around once in a while (and you wait for it) is not good for you! find someone good for you and your son. He will always be his father and hopefully a good one but that on and off is slowly tearing you down, Think of what YOU want your life to be I wish you all the strength you need to find someone for the long haul, and above all be there for yourself and your son.