Strong coupling lattice QCD in the dual representation allows to study the full μ-T phase diagram, due to the mildness of the finite density sign problem. Such simulations have been performed in the chiral limit, both at finite Nt and in the continuous time limit. Here we extend the phase diagram to finite quark masses, with an emphasis on the low temperature first order transition. We present our results on the quark mass dependence of the critical end point and the first order
line obtained by Monte Carlo via the worm algorithm.