If I'm a member of the Crown Ward Class Action case, can I still sue for the sexual abuse I suffered while in the care of Children's Aid?

Yes, you can. Since the Crown Ward Class Action case is only against the Ontario government for its failure to pursue legal action, you are still able to sue Children's Aid for the sexual abuse that happened to you while in its care.

You might be entitled to compensation through both the class action as well as your individual lawsuit. One does not prevent the other.