He can't leave you alone because he's been getting something out of what he's doing. Originally, it was ego strokes because you reacted to him. Now that you've determined to grit your teeth and ignore, he's redoubling his efforts in an attempt to break you. Not 'break you' to destroy you, but 'break you' to get what he needs, despite the pain it may cause you. So you see, he's just as narcissistic as his mother! It's all about him and what he needs. Heck, he probably doesn't even consciously realize he's doing it, not that that's any excuse.
I was hoping he was going to 'ramp it down', but on second thought this is probably going to continue until you leave and it may actually get worse as he realizes you really are serious. This is why it's very important to make your exit as soon as you possibly can. Or at the very least, try to arrange your life so that you spend the least amount possible at home.
For now, try to stop thinking 'when will he stop' and start thinking 'only X more days' when he pulls his shit. It's rather like any difficult or painful task. You can't focus on the pain, you have to focus on the 'end result'.
One other thing, try to focus the purpose of your actions on yourself. You are doing them for you. You shouldn't be doing them to 'show him' or 'sauce for the goose, etc'. So if you're going out, don't get gussied up and go out to 'show him what it feels like' or to prove anything to him. Do it because you want to expand your horizons. If you ignore him, do it because it's healthy for your recovery to mentally separate from his actions, not to show him you don't care. It's a subtle thing, but it's important.