I am a Ukrainian citizen, married to a Canadian citizen, our marriage lasted just for few months, now I live in Ukraine, so we are separated for about 2 years, but I can't get a divorce from my husband on some unclear reason... Is this marriage valid in EU countries?

As far as I know, a valid marriage is recognized in most countries.

If you are unsure, speak to someone at the Canadian consulate for advice.

Yes, they are "valid" so get a clear reason why you can't get a divorce.