Does she know he's gay?

Oh my God, how could she NOT know he's gay? He's constantly dashing off to the "Ranch" to "check on things", he accessories her outfits to withing an inch of her life, they sleep on opposite sides of a custom-made bed that looks like it was created for the express purpose to host orgies: I had him pegged LONG before the under the table hand holding scene. I look forward to this series kicking into high gear, it's gonna be a hoot and a holler!

Truth is, everybody is going to hurt you; you just gotta find the ones worth suffering for

When i saw the bed scene, I honestly thought they were swingers. But, it's very obvious that he's gay, and she knows it.

Yes, she knows he's gay. In one of the first episodes they had a whole conversation about his lover/foreman who left him because he had to get back to Dallas for his daughter's cheerleading performance.
She has said, more than once, that she loves him and stays with him because he's the first man to tell her she's beautiful and to love her.
She's got major Daddy issues, and her husband is a man who lets her be tough and still love her. Almost like they compliment each other's personalities and gender roles.