With the I-601A provisional waiver, you will not have to depart the U.S. while your application is pending. If your I-601A is approved, you will be able to leave the U.S. and attend an immigrant visa interview abroad. At that stage, you will have peace of mind knowing that you have the approved waiver in your hands, and you will be able to return to the U.S. to be reunited with your family soon.
Form I-601 and I-601A have a different process and requirements. You can only file a Form I-601A waiver if you are inadmissible because you have incurred the 3-year or 10-year bar. You can file a Form I-601 waiver if you are subject to other bars.