Photo: Jon Feingersh, Getty Images Adapted from a recent online discussion. Dear Carolyn: My little sister (late 20’s) got married last year. Within months she found out her 30-year-old husband was cheating on her with a barely legal cashier at his job. They tried to work things out, only for my sister to discover the affair was still going on and predated the wedding. She decided she was done, only now she was pregnant. I decided to invite her to live with me and my family, which involved buying a new (and much more expensive) house. Now she has decided to try to work things out with her husband, and will probably break her promise of a several years’ stay in our home. I can afford the new mortgage without her financial contribution, but not without serious lifestyle changes. Photo: Denkou Images/Getty Images/Cultura RF Need advice? Here are our readers favorite Carolyn Hax columns. Need advice? Here are our readers favorite Carolyn Hax columns. Photo: Denkou Images/Getty Images/Cultura RF Photo: Niko Guido/Getty Images Photo: Justin Pumfrey/Getty Images Photo: Stewart Cohen/Getty Images/Blend Images Photo: Maskot/Getty Images/Maskot Photo: Caiaimage/Sam Edwards/Getty Images/Caiaimage Photo: Mixmike/Getty Images Photo: JORDAN STEAD, SEATTLEPI.COM Photo: Rebecca Ellis/Getty Images Photo: Franckreporter/Getty Images Photo: JGI/Jamie Grill/Getty Images/Blend Images Photo: Hannes Hepp/Getty Images Photo: JGI/Jamie Grill/Getty Images/Blend Images Photo: Izabela Habur/Getty Images Photo: Stephanie Rushton/Getty Images Photo: Ilana Kohn/Getty Images/Ikon Images Photo: Hero Images/Getty Images/Hero Images Photo: Andy Ryan/Getty Images Photo: Frederic Cirou/Getty Images/PhotoAlto Photo: Stephanie Rausser/Getty Images Carolyn Hax: Should…more detail