The Haldane model was invented to introduce the Integer Quantum Hall Effect without Landau levels. It describes non-interacting spinless electrons on the honeycomb lattice with real n.n. and complex n.n.n. hopping amplitudes and inversion symmetry breaking on-site energy \pm \Delta. We study the phase diagram of the interacting spin-1/2 Haldane model with chiral phase \phi = \pi/2 at half-filling. Both on-site and long-range Coulomb repulsive interactions (Haldane-Hubbard-Coulomb model) are considered. The problem with on-site interaction U alone was addressed in the past by a variety of approximate and finite size methods that produced results in disagreement with each other both quantitatively and qualitatively. Conventional Quantum Monte Carlo methods, capable of dealing with “reasonable” system sizes, are ineffective here due to the notorious fermionic sign problem. In our work we employ the Diagrammatic Monte Carlo technique, developed for graphene-type systems, to (i) accurately locate phase transition points to the topologically nontrivial phases in the (\Delta, U)-plane and (ii) demonstrate the strong effect of typically discarded in theoretical considerations long-range part of the Coulomb interaction.