The What If Syndrome

Hello everyone
     We, my two cats and myself are very happy and settled here in our nice flat, the rent's paid, all the bills are paid, I have broadband, an old but very reliable car, warmth, enough food and am easily working enough hours to pay for everything and still have money left over. Yes, things are looking up, so why am I afraid?
        I'll tell you why, It could all come crashing down. Its happened before, made redundant and ended up homeless all in the space of a month. I am suffering from a severe case of the 'What if's'.
I'm afraid to relax and really enjoy myself because I know how quickly things can change. What if the landlord decides to sell? Or wants me out for some other reason, what if I lose one or more of the six jobs I'm doing and can't pay the rent?
     I am working ten, sometimes 12 hours a day, seven days a week just so that I can have some money saved up should disaster strike again. I should be enjoying what I have, but my constant fear of becoming homeless again is stopping me from really appreciating and being able to enjoy what I have.
     My novel, however is coming along in leaps and bounds and is almost finished, only two chapters to go, then comes the BIG edit. I have also written three short stories and sent them off into the world. Writing seems to be an escape from reality at the moment and allows me to think of something else and not obsess over my own fears. Also a couple of my jobs are office cleaning, where a brain is not required, this then allows my body to go onto autopilot and my mind to think over difficult plot ideas and new stories, so when I do finally get a few free hours here and there to do some writing, it's pretty much all there filed away inside my head, or on various bits of scrap paper screwed up in my pocket, or suffocating in the depths of my bag.
     That's about it for now, but if anyone out there knows how to stop the WHAT IF syndrome, it would be very much appreciated.