Make a list of safe small talk. The weather, dinner, hows work, how is your daughter doing in school, your daughters friends or ask her how her day is gong. People do this all the time in a social environment where they meet somebody they may never see again and sometimes they don't even care about the answer. If you start talking, the conversation might move to something more important. If nothing else, your daughter will see that you are both civil to each other and will feel comfortable when she is around both of you.