I was divorced on Dec. 2018 but all other issues like alimony were finalized by the judge on august 2019. Do I need to claim the Alimony I received?

Your question doesn’t quite make sense. You can’t be divorced unless there is a final divorce order put in place by a judge.  The judge could have modified the order afterwards, in order to settle certain things. But there must have been a final divorce order before December 31, 2018, or else you were not divorced.

in the case of a divorce that is finalized before December 31, 2018, and then modified after January 1, 2019, the parties have the option of stating in the modification that alimony will no longer be taxable and deductible, or they have the option of leaving things as they were under the law prior to December 2018. So you will need to read your original divorce order and your modification very carefully. It could go either way, and I can’t tell you which way it will fall.  You may need to take the original divorce and the modification to an expert to review.