As I recall, he recently camped outside your door after you briefly kicked him out, after which you let him back in. Can you tell your landlord or doorman or whoever that he is NOT welcome and to call the police to have him removed if he shows up? He is trespassing on THEIR property, too.
And if he persists, look into filing a protective order based on stalking. I believe in Illinois you don't have to show you're in fear of physical harm, but are experiencing emotional distress. If he keeps bothering you after you've put him out, I think that probably qualifies, though your local DV advocate could advise you more accurately.