Wedding song first dance help please!?

My fiance's mom was a singer back in the day, and while he doesn't have many great memories of his childhood he's mentioned she used to sing Patsy Cline "Crazy" to him all the time and that that was a fond memory. In fact he even got teary eyed when we heard it on the jukebox while we were out. I was thinking of asking his mom to sing this at our wedding for our first dance, because I know it would be really special and have great sentimental value to him, but after looking at the lyrics I don't really know that it's a great song for a wedding...it seems like it's kind of sad like she's singing to someone who's hurt her and left her...now I'm torn...what are everybody's thoughts on this as a wedding song?