I'm thankful your daughter has given her life to Jesus Christ, and I have no doubt that she has found a joy and peace that were lacking in her life before this.But I'm sorry she's reacted toward you in a negative way -- and no, this isn't the way she should be acting.
Jesus taught us to love others, just as He loves them (even if they don't love Him in return). He said, "A new command I give you: Love one another. As I have loved you, so you must love one another" (John 13:34). In time, I'm sure your daughter will come to see this truth more clearly.
Since receiving your letter, I've been pondering why your daughter has reacted in this way. I wonder, for example, if she resents the fact that you never taught her about God or had any interest in God. But I also can't help but feel that she's very concerned about you -- and her concern comes from her love for you. She hopes that some day you'll discover what she has discovered, and that Christ's peace and joy and hope will become a part of your lives, as they have hers.
Whatever her reasons, my prayer is that you and your husband will begin to face your own need of Christ. God loves you, and life's greatest joy comes from knowing Him and being able to face the future with Christ in our hearts.