Any tax on selling my share of a partnership in 2019?

I was a general partner in a  partnership for 10 years that owns an apartment building. In 2019 I sold my share of the partnership to one of the other partners for what I initially invested.  I received a down payment and monthly principal and interest payments in 2019 based on an applicable 72 month amortization table.  I received a 1099 for the interest I received. No tax forms received for principal received. I ended up receiving the balance of my initial investment in January of 2020.   For 2019 taxes while having to declare the 1099 interest as income, I don't think I need to declare the down payment and principal payments received in 2019 as capital gains or ordinary income because I'm only getting back what I initially invested in the partnership.  Appreciate any insights and input.  Thank you.  TC6375