"Your wife is not having an affair. "
RockRose has no idea if she is or isn't. She has no idea who your wife is. She thinks your wife has a right to be constantly messaging men who fancy her. She works with this man, most of her time is spent with him at work, before and after work she feels it's necessary to be texting him still. Her attention isn't with you. It's with this man. To me, that is cheating. If she isn't cheating, then she is leading this man on. We know he fancies her, you've see the flirtatious texts. Both are almost as bad as each other as a married women.
You definitely need to talk to her.