I want to make a very clear claim here, as a Spaniard who lived in Menorca (one of the so called "Paixos Catalans", what the expansionist independentists call "their territories"). I used to speak Catalan (or rather, their local dialect). I was raised there, and I had a lot experiences that well, I think it's not the point of this.

What I want to say is: many, if not most, Spaniards (non-catalans) do actually support the idea of holding a referendum, me included. The problem is that it's constintuationally illegal, and we should have changed the Constitution for that. And we should have. However, is not that clear who should be allowed to vote there. The land of the Catalans belongs in theory to all the Spaniards, in the same way that the rest of the lands of Spain belong to the Catalans. Who is Catalan is also hard to define, since we all have Spanish passport. If I live there for 5 years, am I Catalan? Well, considering that a big majority of catalans do actually have family from other parts of Spain, is hard to argue there is any kind of pure genetic lineage.
In theory, we should have allowed all Spaniards vote first on holding a referendum or not. And then also ask "the Catalans" under a clear definition of _who_ is Catalan and has the exclusive right to vote on the right to rule that land. Perhaps also we should have voted on different regions, since there are parts that don't want to be independent, or perhaps just want to be independent of Catalonia altogether (such is the case of Vall d'Aran).

Many people seems to have a very easy time blaming Spain of being an authoritarian country, without understanding the depth and complexity of the problem, or that what a government does doesn't represent what all the people want. They were not voted in to do this, they were voted because the other alternatives failed to deliver in many ways in previous mandates. It was a reactionary voting. There are many people in Spain claiming for referendums. And also many people in Spain that see the independence of Catalonia the only way to keep advancing as a country where other less favoured regions could also prosper.

Honestly, I wish people from other countries would double-check facts and go deeper in understanding the situation. While I'm very ashamed of what the police did in the votings, there is a longer story behind all this that has been sadly summarized by videos and pictures of that violent day. That was a terrible mistake from a government I don't feel identified with.
I'm both ashamed of Spain and of Catalonia. I whish we knew how to live together. We are both going to do worse now. We are a fractured society. Both sides. Both sides lied, both sides manipulated.

Spain is a country of many cultures and languages. We could be an example of the world. But we are not. No Catalonia is not the only region with historical differences. Andalusia was the cultural center of Europe in the 10th century. Euskadi is an industrial powerhorse. Galicia has celtic roots. Canary Islands is a beautiful mix of Latin American culture, Africa and south Spain. And so it goes for many other regions.

As a Spaniard, I believe the best course of action is to split the country (sorry, I still don't buy that Spain conquered Catalonia, that just never happened, so yes, split a 500-years old country is the accurate definition).

‘I am firmly convinced that Spain is the strongest country of the world. Century after century trying to destroy herself and still no success’ - Otto von Bismark

Well, actually maybe is time to try to start all over again. But please, check all historical facts and try to read both sides of the story. Don't buy that the Spaniards "are retrograde, old-fashined, stubborn, imperialistic, etc...", and the Catalans represent all good that happen in Spain, because that's unfair and untrue.