Retirement tax questions

This has nothing to do with 2020.  I received the distribution in 2015 and received a 2015 1099-R for the same amount.  When I took the distribution out in 2015, I was under the impression that it would not be taxable as long as I paid this back.  I did pay the entire amount back with interest over 3 years.  

My question was:

Do I pick up the 1099R for the entire amount and if I do is there any way to offset it by what I paid back in 2015, 2016 and 2017? My taxable amount Box 2 is the same as Box 1.

I never filed my 2015 tax return or 2016 and now need to but want to do this properly. 

So from what you are saying I am fully taxed on this distribution?