First off, since she married a Baptist, her decision to become a Baptist probably has a lot to do with that. And since she was a Catholic who dated and married a Baptist in the first place, she probably loves Jesus but doesn’t know a great deal about the Catholic faith, (but since she was brought up Catholic, she may think she does, and she may know more about it than a lot Catholics she knows.)
The Sacraments are one source of Jesus’ grace that He gave us. (There are other sources of God’s grace. He’s not limited by the Sacraments but He does work through them.) We have faith in Jesus, and we believe He instituted the Sacraments as a way to “tap into” His grace. One might even say that our faith in Jesus is what gives us faith the Sacraments He gave us. It might help if you’re familiar with the Bible verses to cite for the various sacraments when talking with a Baptist, but don’t overload her with Bible quotes. Just be familiar with the Bible as many Baptists know the Bible well. It might also help if you could share a personal story about how you’ve experience God’s love and grace through the Sacraments.
I’m sure there are lots you could say, but I suggest you start by listening. Just as you listened when she shared what she thought Catholic believed about the Sacraments, listen to her faith journey. Then share your faith journey. And you might want to begin and end your discussion with her by praying together and pray in preparation for your meeting.
Have a nice time with your friend!