Firstly, you don't sell your house nor do you borrow against it. I can fully understand your desire to fly for a living because I too had the same aspiration as you. I left proper full time employment in 1989 and it took until 1993 to get my first job as an F/O. Fortunately I still had my parents' house to live in and some savings but more importantly, no dependents.
The world for those aspiring towards a career in aviation has changed since I started. For a start we are in a dreadful economic slump. Secondly, there are a huge number of qualified pilots looking for work and thirdly, as ever, there is a glut of wannabes. Some of the wannabes are so desperate, they'll pay for line training as well as their own type ratings. This is clearly bonkers. But what is means for you is that it is most unlikely that you'll get a job for a few years after you qualify, unless of course, you get lucky.
As for the reason airlines won't take older F/O's - well some do. But it is a fact that the older you get, the longer you take to train and adapt to new procedures. However, most reasonable airlines don't have a problem with age once you are in. The problem is with the prats in the Human Remains. You have get past them first to get your job. And you may well have a better chance of winning the lottery than getting past them. They have their own set of criteria for pilots recruitment which they'll apply even to the detriment of their own operation.
My advice - take up gliding, aerobatics or vintage aircraft and stick to the day job. Flying won't be rewarding new entrants for a few years yet.
PM