You were not a terrorist because you did not participate in the terrorist activities, and refusing to speak Spanish is not a terrorist action (and should not be a criminal offense anyway, just complicates life). Exiling the whole family of a terrorist may be too harsh, depending on the circumstances. But the people who were blowing up civilian cars, buses and trains were terrorists, by the definition, whether you agree with their actions or not.

According to Wikipedia, there were civilians in those cars the ETA blew up.

So yes... the ETA is definitely a terrorist organization.