Increased Income/Taxes and Repayment of Severance

I have been using TurboTax for 10+ years and have a question regarding severance repayment and associated accounting

 

My job was eliminated in November, 2018 and I received a severance package amounting to ~9 months of pay (one month for each year of employment).  

 

I requested the severance payment be deferred to January, 2019, to avoid the Tax nightmare, however the request was declined and I received the severance check in December, 2018 which bumped my and my wife's 2018 income into a higher Tax bracket for the year.

 

In early 2019, I was rehired and asked to repay 6 months of severance; which I did. Although I have asked my employer to adjust my 2019 W2 to reflect/deduct the repayment of severance, I have a number of questions:

 

1. Can I submit amended/revised 2018 returns to account for the repayment of severance (although it was not repaid until February, 2019)?

 

 2. I assume that showing the repayment  on my 2019 W2 will not allow for us to capture the ~3+% we had to absorb/pay on our total 2018 income due to being bumped up to the higher Tax brackets. How can I correct these issues?

 

3. Any other advice?

 

Thank you for your time and consideration to this matter.