We have measured the correlated center-of-mass (c.m.) motion and energy sharing of the three massive Coulomb-interacting particles ${\mathrm{H}}^{+}+{\mathrm{H}}^{+}+{\mathrm{H}}^{\ensuremath{-}}$ with total energy of a few eV. We measured in time coincidence the lab frame energy and angle of all three particles produced from excited 4 keV ${\mathrm{H}}_{3}^{\phantom{\rule{0ex}{0ex}}+}$ formed in collisions with He. For each triple coincidence, we found the c.m. energy of each particle and the c.m. correlation angle between the two ${\mathrm{H}}^{+}$. The c.m. energy data, displayed on a Dalitz plot, reveals the high degree of correlated motion of the three massive charged particles.