  We report a 20-year campaign to track the 1.8 hour photometric wave in the
recurrent nova T Pyxidis, using the global telescope network of the Center for
Backyard Astrophysics. During 1996-2011, that wave was highly stable in
amplitude and waveform, resembling the orbital wave commonly seen in supersoft
binaries. The period, however, was found to increase on a timescale
P/P-dot=3x10^5 years. This suggests a mass transfer rate in quiescence of
~10^-7 M_sol/yr, in substantial agreement with the accretion rate based on the
star's luminosity. This is ~2000x greater than is typical for cataclysmic
variables of that orbital period. During the post-eruption quiescence
(2012-2016), the star continued on its merry but mysterious way - similar
luminosity, similar P/P-dot (2.4x10^5 years).
  The orbital signal became vanishingly weak (<0.003 mag) near maximum light of
the 2011 eruption. By day 170 of the eruption, near V=11, the orbital signal
reappeared with an amplitude of 0.005 mag. It then gradually strengthened to
its normal 0.08 mag amplitude, as the star declined to its "quiescent"
magnitude of 15.7. During the ~1 year of invisibility and low amplitude, the
orbital signal had increased in period by 0.0054(7)%. This is probably a
measure of the mass ejected in the nova outburst. For a plausible choice of
binary parameters, that mass is at least 3x10^-5 M_sol, and probably more. This
represents >300 years of accretion at the pre-outburst rate, but the time
between outbursts was only 45 years. Thus the erupting white dwarf seems to
have ejected at least 6x more mass than it accreted. If this eruption is
typical, the white dwarf must be eroding, rather than growing, in mass. Unless
the present series of eruptions is a short-lived episode, the binary dynamics
appear to be a mutual suicide pact between the eroding white dwarf and the
low-mass secondary, excited ... . (etc., abstract continues)
