I don't think you should do it. Sure its sex and all. But she has kids so that right there is the main problem. How could these kids look up to a whore mom. Sure they might never find out, but she'll still be a whore. And what if the kids walk in while you two are at it. "Daddy daddy! A man was here jumping up and down on mommy!" There are just somethings that should not be done, like sleep with a woman who has kids and still has a man. And since you're looking at this like some 1 hour fun excersion, thats even worse. But if her and her man separated, and you were serious about taking care of her and her kids then it would be alright. Here's my advice, watch The Graduate and see what happens when a young man such as yourself sleeps with a woman that he knows that has a child.