Quoting JessieLeeAnne:" It will probably be soon. I have been in your spot before. You need to save your money in a secret ... [snip!] ... Sorry for intruding, but the situation sounds terribly unhealthy. You don't tell him you are leaving him, just do it. "
All of this :!::!::!:
Don't tell him anything. Just leave and get out while you still can. It's better for you and your child.
Again i agree, i've been there too. I first left when my LO was a baby, it has been an ongoing battle but far far better than if i had allowed him to be around us all the time.