My grandmother also. It's amazing how many in the US not only don't know about this, but become angry when you tell them.
Yet for the generation that lived through WW2, you can talk to anyone who was on the wrong side of the iron curtain and they will tell you what it was like.
The BBC documentary World At War (1973) covers this in episode 21. https://www.dailymotion.com/video/x3oeao1
This is also covered on Wikipedia now https://en.wikipedia.org/wiki/Rape_during_the_occupation_of_...
"Female deaths in connection with the rapes in Germany, overall, are estimated at 240,000.[2][17] Antony Beevor describes it as the "greatest phenomenon of mass rape in history", and has concluded that at least 1.4 million women were raped in East Prussia, Pomerania and Silesia alone.[18]"
In Hungary:
"According to Skrabski, it’s possible that as many as 800,000 Hungarian women were raped, and the violence included gang rape and sexual torture. Pregnancy resulting from rape was so widespread that the government suspended its ban on abortions for several months during 1945, offering abortion and STD treatment services free of charge." https://www.washingtonpost.com/blogs/she-the-people/wp/2013/...
There are many well documented stories of these atrocities in all the areas occupied by the Red Army, most too gruesome to include here. Anyone can do their own research, the information is out there, even if many don't want to hear it. When you want to understand why Eastern Europe is falling over itself (foolishly, IMO) to join NATO and integrate into the West, these types of things need to be understood as being in the background.