Please, my darlings, grasp an eternal truth: discovering that your own government/side/etc is actually kind of shitty means that you stop and apply critical thinking to what they have taught and the positions they espouse. You use your thinking brain to dig into evidence and evaluate assessments and so on.
It does not mean that you swallow the opposite view whole-hog without pause because, and I really need you to understand this: in any situation of opposing views both sides can be wrong.
A conflict does not magically transform one side into righteous defenders and another side into horrible monsters: both sides can in fact be really shitty.
The USSR, and for that matter the modern People's Republic of China, are excellent examples of "just because you profess to espouse a certain set of values, and even believe you do, that will not save you from actually being a horrible shitty evil person who acts in direct contravention of those values", or shorter form: ideology does not guarantee ethics. They murdered their own people on a scale it's genuinely difficult for us (that is, people in Canada, the US, the UK, etc) to imagine because we are incredibly privileged in that regard and yes I say that being well aware of the blood on our nations' hands; and the USSR was, and the PRC is, colonial, imperialist powers on par with any others you already consider appalling.
Yes, they were all those things while claiming the ideology of equality and worker's rights and so on. The ability of a system to lie about its motivations and functional systematic purpose should not be such a surprise, given that you've had it with our own. And yeah, if you're just coming to those ideologies it's pretty goddamn depressing to have to grapple with the fact that pretty universally systems of government that have actually arisen from them - especially after violent revolution - have tended to end up just as horrible and corrupt and violent as what they replaced.
(Turns out the problems of human violence towards other humans are not just accidentally inflicted on us by somehow stumbling into the wrong kind of systems, but are a really messy complex set of interactions between our individual and group traumas, how patterns of power/etc already work, how we interact with groups outside of our own and their dynamics, and . . . so on. And also turns out that you should be universally and incredibly wary of anyone who tells you that all you need to do is violently get rid of the Wrong People, who are Bad and intrinsically different from proper people, and that once this happens everything will naturally fall into place for the benefit of those remaining. Yes, even when those Wrong People are obviously doing bad things.)
But yeah: there were fucking gulags. Your neighbour just . . . disappeared. Members of your family just . . . .disappeared. Entire violent purges of a whole level of government happened. So did bloody imperial conquest.
The USSR was a fucking shitshow.