Dynamics of a simple system, such as a two-state (dimer) model, are dramatically changed in the presence of interactions and external driving, and the resultant unitary dynamics show both regular and chaotic regions. We investigate the non-unitary dynamics of such a dimer in the presence of balanced gain and loss for the two states, i.e. a $mathcal{PT}$ symmetric dimer. We find that at low and high driving frequencies, the $mathcal{PT}$-symmetric dimer motion continues to be regular, and the system is in the $mathcal{PT}$-symmetric state. On that other hand, for intermediate driving frequency, the system shows chaotic motion, and is usually in the $mathcal{PT}$-symmetry broken state. Our results elucidate the interplay between the $mathcal{PT}$-symmetry breaking transitions and regular-chaotic transitions in an experimentally accessible toy model.
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