There are not enough facts here to get a complete picture of the issues.
Having said that, the decision to leave (or opt-out) a class action to pursue your own case is not one to be taken lightly. Unless the potential recovery is fairly sizable, it will be difficult to justify paying an attorney to handle the case or to find an attorney willing to take it on a contingency basis.
Also, it is not clear what you mean when you say "the case has been decided in the plaintiffs favor." Does that mean the judge certified the case as a class action? Does it mean the judge ruled on a summary judgment motion? Most cases proceed along a fairly well established timeline. Knowing where the case is on that timeline will help someone to guide you to possible actions.
Best of luck.
I agree completely with Mr. Savett's thoughtful response. I would like to add that you need to find out whether the existing class action is on behalf of a national class or whether it applies only to residents of the "other state" in which it was filed. If it is on behalf of a national class, you may not need to do anything to protect your rights. However, if it is only a class for residents of another state, you should look into bringing claims on behalf of residents of your state, too.
Legal Information is Not Legal Advice My answer provides information about the law based on the limited information provided in the questions asked and is not intended to provide legal advice or opinions, and does not constitute an attorney-client relationship. The answer to the question is for educational and informational purposes only. The law differs in each jurisdiction and may be interpreted or applied differently depending on the jurisdiction or situation. Accordingly, I highly recommend that you consult with an attorney to discuss the details of your problem so you can get legal advice tailored to your particular circumstances.