Yeah, the woman has issues and is looking to you for validation. You're her escape from either a bad home life or her boredom of being a wife and/or mom. The exciting, friendly coworker. If you truly are a nice guy, you'd tell this woman firmly but respectfully to back off and keep things strictly professional from now on. For your own benefit, save all the messages in case she tries to make trouble at work, evidently she's not exactly full of great ideas. She's going to find someone to act out her fantasies with, but you don't have to be the scumbag who enables a married woman to sneak around.

"Look [her name], it has been fun talking to you but I've already asked you a few times not to say these kinds of things to me. I find it inappropriate, you have a family at home, and while your home life is none of my business I don't really want to have these talks with you knowing you have a husband. This is the last time I'm going to ask, please stop texting me things of this nature so it does not become an issue at work."

Tell her that. If she keeps doing it, block her, only speak to her at work when needed and report her to HR/management if she still tries to pester you.