Sad is the word I'd use
As I've known people to concoct whoppers of similar proportions - a friend of mine at school invented a similarly unbelievable imaginary girlfriend (who we were, of course, never allowed to meet) and even took offence on her behalf when we started up a running joke that she must be a sheep. The amount of effort he put into making up details of their relationship - however unbelievable - was staggering.

There was also the chap who claimed that he'd managed to drive round the M25, twice, in a VW Beetle, in about half an hour. When laughed out of court he backpedalled to "oh, well, maybe I just went round it once..."
(LongJohnBaldry, Wed 27 Oct 2010, 13:26, Reply)