How can you tell if his love for you means more to him than the love he had for his ex-wife?

You can't consume yourself in what his love was for his ex-wife, but take the love he is giving you in present time or he might start to feel his love is being neglected because of his past. If that happens, he may stop giving his love altogether. So long as he isn't constantly reminiscent of her and comparing you to her, you shouldn't worry about it so much or compare yourself to her.