Conversation with my daughter in law

Hi, I am new to this blog and would like to share my new experiences being a free, saved, child of an amazing God.
I am the mother of 13 children. Not unusual for a good 6th generation Mormon. When I finally came to realize that I wanted to leave I wondered how my older kids that are still in the LDS church would react. It has been an interesting journey these last 3 years.
My second son, I'll call him Zack, and his wife and 7 kids came over for a birthday celebration. His wife, "Sally", and I were sitting together. She is currently enrolled in an Old Testament course through BYU. We got to talking about the law of Moses. She asked me "I wonder what rules God would make up for the music of our day". I got up and chickened out. I walked into the kitchen and started to clean up. She followed me. I had a chance to talk about how the law of Moses was for their benefit and that when Jesus Christ came it was done away. I totally chickened out at that point.
I have thought about it for a couple of days now and thought I would write my response here. I hope she reads it.
I would say to her,"God did away with all the rules to live by, instead He indwells in our lives. It is His voice that we hear when we don't put ourselves into a religion that can come between you and HIM." He could tell you Himself if the music you hear is offensive to His relationship with you."
She made a commment about her being a Christian woman. Here is what I would say to that, "Well I don't consider myself a Mormon. Why do you consider yourself a Christian?" I would then have to listen to the response that she believes in the Atonement of Jesus Christ.
Well do you believe that you gain salvation through that Atonement?
Yes.
Then what are you striving so hard to acheive?
WEll you can't just get there without doing anything.
But in Ephesians 2, Paul talks about being saved by grace, not works. I would want to get the Bible out and look up the scriptures and hold her and tell her and pray with her. She is a strong one and I think if we can get into it and I can really be brave, she would see and understand.
She might be a little devastated, she lives in that Mormon perfect fantasy. I hate the fantasy. Pray for me. God is faithful and in His time and way she will be His.
Love, R:)