Bleg: Who originally did this song?

"If I'd known last night was our last night, no more to look forward to...I would have given more of me, and taken more of you...then perhaps instead of lettin' go, you'd still be hangin' on...If I'd known last night was our last night, I would have loved you all night long..."
For some strange reason that song sounds very familiar. I just heard a version of it by a guy named Ron Williams, Leona Williams' son and Merle Haggard's stepson. Never heard of him before I got Sirius, but he sounds really, really good.