Looking for Sabina McCue and possible connection to Martin Collins

I recently discovered that my paternal great-grandfather Martin Collins (b. ~1820, Ireland) was married to a Sabina McCue (b. ~1830, Ireland) before he was married to my great-grandmother Margaret Smith (b. 1840, New York). Since I know so little about Martin's life/death and even less about Margaret's, I'm hoping that if I find information about Sabina, I might find out more about my GGF. I don't know exactly when either Martin or Sabina emigrated to America (there are 7 or 8 Martin Collinses who appear on immigration records in the early 1850s who were about the right age) and I can't find any record of Sabina's emigration to America at all. I do know that by 1853 they were both in Indiana, USA, where they were married in Shelbyville, Shelby Co, Indiana, on 11 Oct 1853. They had at least three children (Bridget, b. 1854, John, b. 1856, and Catherine/Katherine, b. ~1860-62. I grew up knowing that Katherine was my dad's aunt, but when I started working on my family tree, I became aware that she was born at least 2 (and maybe more) years before Martin married my GGM Margaret. I never heard of Bridget or John or any other siblings and I doubt my dad was aware of them. (Dad's mother died when he was a little over a year old and his dad, my grandfather William Collins, gave the children away, so Dad knew little about his biological family.) Anyway, I haven't been able to find out what happened to Sabina. Did she die? Were they divorced? Seems unlikely because I know they were Catholic. And my GGF Martin is just as elusive—I've only found him on three official records: the 1870 census in Shelbyville, by which time he was married to Margaret, and all of the children are there—Bridget, Johnny, and Katie from Sabina and Martin, Michael, 2 yrs old, and Margaret, a baby from the marriage to Margaret. I presume Michael and baby Margaret died young; and the two marriage records—the one to Sabina and the marriage registration dated 22 Jun 1864, also in Shelby Co, IN, for his marriage to Margaret. He doesn't appear on any other census and I haven't found a death certificate. Same for GGM Margaret. They both lived at least long enough for my grandfather William Collins to be born in 1876, and he was the youngest of the 3 children I know of. My fervent wish is to someday find out where in Ireland Martin was from, and in finding information about Sabina it's just possible that might lead me to more info about him. Since they both wound up in Indiana, which wasn't a place that most immigrants from Ireland went to, I'm thinking it's possible they might have known each other or at least each other's families back in Ireland. Any information will be gratefully received. Thanks.