J.W.
The fact that you stated he was abusive pretty much explains how messed up this person is. He may be narcissistic. He may rewrite history even in his own mind to build himself up to be the person he thinks he should have been. He probably is chameleon-like -- empty -- taking on traits he thinks others want him to be. He himself is not real. He obviously has a severe personality disorder, so asking why he lies is like asking why a twisted person is twisted. It is the way he is put together, so to speak.
You probably got involved in the first place just because you were emotionally vulnerable at the time. Abusers prey on that. It probably fell apart when you got stronger. Now, with his facebook page, he is weaving yet another spider web.
You might want to read some wonderful books by Patricia Evans. This one is about understanding what she terms controlling people http://www.amazon.com/gp/product/158062569X?ie=UTF8&t...