There is no way of being certain that your fiancée is not still in love with her ex husband, as it is common for many people to re-marry and still have feelings for their ex. However, this does not mean that you mean any less to her or that she loves you any less. If your girlfriend has agreed to becoming your wife, then this is a sign that she is ready to move on and wants to be with you. The only person who truly knows the way that she feels is her, so talk to her about it. Don't try to interpret her actions yourself until you have heard what she has to say.

If your girlfriend is engaged to you, then she is over her ex-husband. She may feel something for him still, which is impossible for people to blank out and ignore, however she is still moving on and has shown her commitment to you. Stop living in the past, she isn't so why should you be?