My guess is that Ronald Reagan caused the collapse by spending billions on Star Wars program.
We also hit them hard in the pocketbook: convinced OPEC/the Saudis to lower the price of oil, directly sabotaged their gas exports to Western Europe, otherwise denied them technology that would have improved their economy, and made Afghanistan their Vietnam.
And then the moral aspect; I haven't read the fine article, but Reagan wasn't afraid to correctly refer to the Soviet Union as an "Evil Empire", told Gorbachev to "Tear down this wall!" (separating East and West Germany). I've also read from accounts inside the Iron Curtain that our invasion of Grenada was a massive shock, this was the first time ever that the West had taken back a Communist nation, explicitly denying the Brezhnev Doctrine, which we also attacked in many ways in Eastern Europe.
Bottom line was that Reagan was the first US President to decide to destroy, rather than merely contain, the Soviet Union, and despite the wavering of George H. "Chicken Kiev" W. Bush, succeeded shortly after leaving office. This, without massive bloodshed, is hands down the greatest geopolitical achievement in post-WWII 20th Century history.
I don't think that affected inter-country morale long-term. What mattered is what happens inside, what we do to each other, how we live. That's true even with immense value that soviet mentality always gave to outside views on it.
"our invasion of Grenada was a massive shock"
I was born in 1985, ostensibly, but I've never heard of this and don't even know where that Grenada is.
Frankly, what you wrote doesn't sound very important to the issue.
I was born in 1993 and I know plenty about the communist-backed coup and subsequent invasion of Grenada. I wouldn't use being born in chronological proximity to an event as a measure of it's geopolitical importance. That said, I've never heard that the US invasion of Grenada was so important in the wider Cold War as to call it "a massive shock". In reality, the collapse of the good ol' USSR is a confluence of events, political, economic, and social that lead to the breakup of world's only other super power. Look at that, the world isn't all black and white and can fit into an online article!
Unrelated, but I think schools should do more to teach kids about history in relation to current major events and issues around the globe. I most adoringly recall my "Current Events" course which was entirely based around teaching the last 150 or so years of major events and the underlying history that lead to those events. At the very least, folks would be a bit better served by learning why Iraq and Afghanistan are the clusterfucks they are as opposed to the Lewis & Clark expedition. I guess what I'm getting at is the US history education pretty much starts on the East coast and ends on the West with not much outside those boundaries.