Kathleen/Catherine Kiely (Kealy) Cashel

Hi I am trying to find Kathleen/Catherine Kealy (variations of spelling)

I am desperately trying to find information on Kathleen Kiely of Cashill Co Carlow.
She was born abt 1879 and her father was possibly James,Frank or Patrick Kiely. In Mar 1908 she is found travelling to the States with her husband, John Weir (my gt grandfather) They married 1 Mar 1908 in Dublin.

What is interesting is, a year later, John married (Apr 1909) my gt grandmother, Sarah Ruxton. They separated about 1920, family stories say Sarah threw him out. We know virtually nothing about John when he left the family - where he went initially, or what he did. All we know is that he died 16 May 1930, in Glasgow. And the interesting part is - His death cert cites Kathleen Weir nee Kealy as his wife?
We had assumed Kathleen had died. How could he marry Sarah? I can't find a divorce. Bigamy? 
Kathleen played a huge part in my gt grandfather's life. I would love to find out about her family, her life, did she have children with John and what happened to her after John's death.
Can you help
Jacqui