What was the earth like before Antarctica was covered with ice? What would happen if it did melt?
Your signature is the answer to the second question 
Antartica was ice free 34 million years ago when CO[sub]2[/sub] was 760 ppm -New CO2 data helps unlock the secrets of Antarctic formation
Current models have CO[sub]2[/sub] hitting 685 by 2050 https://www.oecd.org/env/cc/Outlook%20to%202050_Climate%20Change%20Chapter_HIGLIGHTS-FINA-8pager-UPDATED%20NOV2012.pdf
If all the ice melted sea levels would rise 3.2m If all the ice in Antarctica were to melt, how much would global sea level rise? How quickly is this likely to happen? - AntarcticGlaciers.org
You didn’t read that page very thoroughly. You missed the last sentence of this paragraph:
So 60 + 3.2 +.24 ~= 63.5 meters
Add in the 6 meters or so of Greenland’s glaciers melting and it comes to around 70 meters total.
Good point.
The Earth has had polar ice on and off throughout its history. Conditions while polar ice caps have been either minimal or non-existent have varied quite a bit. At times, the Earth’s temperatures between the equator and the poles did not vary anywhere near as much as they do now. Basically, picture the area around the equator being roughly what it is now, temperature-wise, with the temperatures slowly cooling until they get to current mid-U.S./European temperatures up by the poles. The temperature gradient between the equator and the poles was much less severe than it is now. Also, picture Antarctica covered in trees.
At other times, picture tropical weather at middle latitudes (palm trees growing in New York, for example), nice warm sub-tropic weather (basically Florida weather) up at the poles, and the area around the equator being so ungodly hot that a significant chunk of life on earth went extinct due to the heat.
The former case isn’t so bad, but the latter case would make life on Earth fairly miserable for all. The latter case is basically the conditions during what is known as the Paleocene–Eocene Thermal Maximum (you can google that for more info), or PETM.
Thermal expansion also contributes to sea level rise. A National Geographic article states that about half of recent historic sea level rise is due to thermal expansion. I guess that might be proportionately less going forward, when ice sheets collapse.
https://www.nationalgeographic.com/environment/global-warming/sea-level-rise/