Resonant structures in the dipion mass spectrum from ${\ensuremath{\chi}}_{c1}(3872)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$ decays, produced via ${B}^{+}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\chi}}_{c1}(3872)$ decays, are analyzed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of $9\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. A sizeable contribution from the isospin conserving ${\ensuremath{\chi}}_{c1}(3872)\ensuremath{\rightarrow}\ensuremath{\omega}J/\ensuremath{\psi}$ decay is established for the first time, $(21.4\ifmmode\pm\else\textpm\fi{}2.3\ifmmode\pm\else\textpm\fi{}2.0)%$, with a significance of more than $7.1\ensuremath{\sigma}$. The amplitude of isospin violating decay, ${\ensuremath{\chi}}_{c1}(3872)\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}J/\ensuremath{\psi}$, relative to isospin conserving decay, ${\ensuremath{\chi}}_{c1}(3872)\ensuremath{\rightarrow}\ensuremath{\omega}J/\ensuremath{\psi}$, is properly determined, and it is a factor of 6 larger than expected for a pure charmonium state.