After all these years, don't you think it is time for you to seek some happiness instead of waiting for someone who will never come back to you?
You are not the only 'single father' in this world and will survive, so forget about that heart attack and start living your own life. First step, get divorced, and then find a woman who will love and respect you and provide a 'real' family.
Good luck, and keep us posted.
You will always be this child's father, but also have a right to happiness - a happy father is a better role-model for a son.