Phase separation of two different isosymmetric phases can occur as a result of their similar ground state energies. We have found such phase separation in a multiferroic system at a tensile-strain-driven morphotropic phase boundary of rhombohedral and orthorhombic bismuth ferrite. We utilize the emergent phase competition in order to implement three-step electric switching of ferroelectric polarization as well as rotation of the magnetic easy axis using electric fields. This observation provides a pathway to phase-competition-driven magnetoelectric devices.