Can this still be considered a primary residence property?

[Wensheng Chen]

I purchased a primary residence property with another co-owner in NYC in 2016. The mortgage loan is 100% under my name. 2 years ago, I moved & converted the property to an investment property, and purchased another primary residence property in Georgia. Now I am in the process of selling the NYC property. I came to know about 1031 a month ago. 

Now that I am selling the NYC property, I have questions about taxes, etc. 
Can the NYC property still be considered a primary residence property since I live there for more than 2 years?
If it is considered as a primary residence,  I don't have to worry too much about taxes. According to the Taxpayer Relief Act of 1997, there are 250k or 500k capital gain tax exemptions based on marital status.

If it's considered as an investment property, then I'll need to prepare to do a 1031 exchange. My question regarding the 1031 exchange is that since the house was deeded between the co-owner and me and the mortgage is 100% under my name, how much $ amount properties I should be looking for as the 1031 exchange? Is it 100% of the NYC sale amount or 50%? 

PS: I was young and naive and got tricked into co-owning the property while putting the mortgage 100% under my name. I didn't know much about taxes etc in the past. :(