In this paper we extend Witten-Helffer-Sjöstrand theory from selfadjoint Laplacians based on fiber wise Hermitian metrics to nonselfadjoint Laplacians based on fiber wise non-degenerate symmetric bilinear forms. As an application we show that results about the asymptotics of the Ray-Singer torsion of self-adjoint Witten deformation, as well as the strategy proposed by Burghelea-Friedlander-Kappeler to derive the comparison of Ray-Singer and Reidemeister torsion, can be extended to nonself-adjoint Witten deformation. This is then used to conclude the equality of complex analytic and Milnor-Turaev torsion, at least for odd dimensional manifolds, up to sign.