I am getting married next month. My husband has two kids from his previous marriage. How do I break the ice?

Break the ice to whom? Your family and relatives? What has it got to do with them? If it's not an issue to you, why do you bother if other people have an issue with your step kids? They are part of your family and outsiders should keep any negative comments to themselves. I suggest introducing the children or thanking them during your wedding speech.