Ukraine didn’t secede from the Soviet Union. The Soviet Union was forced to disband itself after a series of screw-ups in the run-up to the the August 1991 coup attempt:
https://www.britannica.com/place/Soviet-Union/The-attempted-coup
When you look at why it failed, you could pretty much map it onto what’s happened with Ukraine.
“What was different this time was that troops who were overwhelmingly Russian were being ordered to move against Russians. The crucial weakness of the plotters was their inability to understand the radical political and social transformation that had occurred in the U.S.S.R. since 1985. It was no longer possible simply to announce that Gorbachev had retired for “health” reasons.”
Soviets attacked civilians in Georgia Azerbaijan, and Lithuania, then expected those states to back the continuation of the USSR. Funnily enough, when a chance came to topple the Kremlin, those countries didn’t wait. Over a course of a very short time period, eight constituents of the Soviet Union (fearing a re-run of the coup), quit the Union. With no real alternative, Russia, Ukraine, and Belorussia established the Commonwealth of Independent States (CIS), and formally aknowledged the end of the Soviet Union as-was. But they did it TOGETHER. Ukraine didn’t unilaterally secede.
It did, however, vote for secession - thereby proving to Russia and Belarus that the USSR couldn’t survive in its old form.
There never was any move to suppress “Russian-language schools, Russian-language newspapers and Russian-language broadcast stations” in all the time that Russia wasn’t trying (unsuccessfully) to hijack the government of Ukraine. All they did was make Ukrainian the official state language.
Of course that attitude changed slowly, first after what Russia did to Viktor Yushchenko to ensure Yanukovych won (which was stupid as he would’ve won anyway), then in 2012 with some meddling over trade agreements, then again in 2013 by interfering with the EU free trade negotiations and subsequently by coercing Azarov and Yanukovych into signing a “generous” bailout agreement that conveniently enabled an annexation by the back-door.
Make no mistake - if Euromaidan protests hadn’t happened, Ukraine would’ve been in default, bankrupted deliberately by Russia before the end of 2015, and Russia had convenient plans to have it’s Men In The Kremlin fly in like white knights.
The Ukrainian language is like Gaelic in Ireland, people claim to speak it, but most do speak Russian.