Determinism and ethics

I might have been mislead, but it seems that when we discussed the differences between determinism and free will, we seemed to come out primarily in favor of determinism. We also discussed how determinism impacts ethical theory by completely negating any kind of morality. Morality implies choice, and determinism does not. So how exactly can we discuss morality under any circumstances if we can not get by this first problem? It seems to me that the construction of morality is just that if we can't get past determinism: A construction. If there is no such thing as morality, then it must be an illusion that we construct ourselves. I really do not like this conclusion, but unless I figure something else out, I must stay behind it.