No EAD or Advance Parole or I-485 is available to you until your priority date becomes current, which will take some 10+ years in the sibling category. And as a sibling, you are not allowed to adjust status if you are here illegally. So you will need to leave the US before you overstay, and then wait outside the US for the 10+ years (unless you can qualify for another visa to stay for a while, like H1B or L1).
If you want to visit the US again during those 10 years, have your sister file the I-130 while you are still in the US, and make sure she specifies consular processing. That way if Immigration gives you trouble on future visits, you can say that you previously were in the US when the I-130 was pending, but you left anyway.