How do you know if she is lying to me?

Her stoires will not add up. Look for clues in your conversations and analyse what she is saying. Usually there will be a certain topic your ex has lied about that bothers you. Write notes on your conversations and a few days or weeks later ask questions relating to the topic. Then compare the answers with your conversation notes. If she is lying you will find differences because usually it is very hard for a liar to keep track of her lies. best of luk