Deception and Lies, How do you tell someone they're doing wrong?

   Last night while walking with my sister Kara and my mom, I got most of the story on what exactly has been going on in Shauna's life. Shauna hasn't been happy with her life for quite a few years. When she got pregnant with Skyler back in 2005, she even told me that she felt her life was over and at an end, which was and is a selfish way of looking at things. Instead of always looking at the positive side, seeing the life of a child as a brand new chapter and a chance to teach that child and love that child, she felt like that child was ruining her life. She had been talking about leaving Chris for a few years, didn't even want to marry him back in 2006 but did because she was pregnant with their second child. I found out last night from Kara that not only did Shauna finally tell Chris she wants a divorce (Tuesday night when she didn't run with me), but she has been cheating on him with another guy who is married as well. I don't know for sure how long she had been doing this but I wouldn't be surprised if it's been over a year. Kara won't say much about it though, and I feel weird because Shauna has been deceiving Chris and been lying to me about things.
   Shauna is my sister, and my running partner but now I feel weird running with her or hanging out with her while knowing these things and knowing that she doesn't know that I know. I feel that I am now a part of this mess and I don't like it, I really feel sorry for the kids though, especially when I know Shauna isn't really thinking about them at all even though she plans on taking them with her. It's weird, especially when I know they should have never gotten together in the first place, it was all out of convenience for both of them but mainly her and now two kids are suffering for it.
   Anyways, other than that my life is going okay for the moment. The business is having to spend money to fix machines while not really making any at the moment. The rails should be finished in 2-3 weeks, which then our Dealers will be ordering, hopefully we can stay above $15,000 until then.