I really need help to set up boundaries with my son?

My son who is now 28 is flying in from Sweden as we speak. A little back ground info. He had a drug problem, and as a single mom I went the whole route, from tough love, to rehabs, to ignoring the drugs, to throwing tantrums to anything you can think of. It was a very long “war” of eight years that I lost. In between all this I was caring for my elderly parents. (With Alzheimer’s).
The main issues his father and I continue to have are the following. He is highly manipulative, he steals from us, and he does not want to work. He cannot hold down a job for more than a month. His dad, my ex husband, always bails him out. Which although well intentioned does not help? He got off crack, but continues to drink, and continues to lie, manipulate and smoke weed. He blames every one for his problems. When he comes back home he does not work, surfs go out all night sleeps all day.
Here is my issue. I was diagnosed bipolar last March. My parents really drained me financially and emotionally for ten years, in between all of this my sons issues I guess everything got too much. Plus I ran out of money anyway I had a breakdown.
I don’t want my son here. He uses people, all the time, for things, money and what he needs. He didn’t even ask me what gran died of. My mom died a few months ago. He is completely self absorbed. I cannot and am not in the frame of mind to deal with him, here in my home. He is toxic. Yes I do love him, of course I do, but I just cannot tolerate his behavior. What on earth am I going to do? Make him stay with friends I am thinking? I need to set the boundaries up now, before he arrives. As because I love him, he tends to walk all over me! I have only just “got my life a little on track” in the last few months. I cannot afford to compromise my health. Maybe I just need “permission” to say no. Which is silly I know. But I have no one else to talk to.