Jealousy is harmful and such behavior can be self-destructive and irrational to your mental and emotional health. It can also ruin your relationship. You should not be comparing yourself to his ex. It's time to work these issues out right now so that you can move on and focus on building your relationship.
Get rid of those negative thoughts and questions. Was she prettier? Was she was a better cook? You probably don't cook at all. She may not have wanted to have kids, but you do. Does it matter really? Stop wasting your time entertaining these kinds of thoughts. Your head will be spinning so much that you won't ever be happy. What matters now is the fact that he's with you, and loves you for exactly who you are. If you spend all of your time worrying what "used to be" with her, you will not have time to enjoy cultivating and wonderful courtship with him.
You should not be asking him questions about her. She does not matter to him anymore and she shouldn't matter to you. Their relationship is history. He has moved on with you. If he isn't talking about her or their relationship all the time, then you shouldn't be either. Let it go! Nobody is perfect. Often times,we women tend to focus more on gaining as man's approval and admiration rather than on how he's actually making us feel or whether he's bringing out the best in us. This leads to a lot of misplaced energy and bad relationship decisions.
Even though men claim not to be emotional, do know, that one of the primary qualities they like about a woman is how she makes him feel about himself when she's around; also whether she is adding or detracting from his quality of life over time. Understand that it was the complete and total package that is you - whom he is attracted to and what he wants. So be yourself. Enjoy your love, be sweet and supportive of him and his family, and treat yourself well. God will bless you and your love.