Should I list myself as a part year resident of nj or a non-resident of nj if i owned a home in nj but moved to ga in 2018?

If you moved to GA in 2018, then for 2019 you are a resident of GA and a non-resident of NJ.  If you have a taxable capital gain on a property sold in 2019 and located in NJ, you would report in on a non-resident NJ return, as well as on your home state GA return.  In that situation, you'd be able to take a credit on your GA return for the tax paid to NJ, so you wouldn't be double-taxed.

Your domicile is where you live and have your driver's license and voter's registration and take mail deliveries and so on. It's the place you return to when you take trips.

If you did all that when you moved to Georgia in 2018, then you were a non-resident of New Jersey for 2019.

Unless you had New Jersey source income (like a rent house - see below), you don't even file a New Jersey return, and if you do, file as a nonresident.

As for the house, did you rent it out after you moved out?

If so, report the disposition of this asset on Schedule E (rental).

If the house was empty (not available for rent), then do a Search (upper right) for sale of home and click on the jump-to link (Mac users need to find sale of home in the Topic List). Enter your sale details here.