Why not preempt her and file for divorce now? If your assets were in Illinois at all relevant times, Illinois has jurisdiction to resolve issues of their ownership.

You can argue that premarital assets should be treated as separate assets; you have a similar argument for post-separation assets although courts usually have more discretion about setting the post-separation date upon which the marital estate should be divided. The big unknown here is, "Where did the money in the accounts come from?"