I certainly hope she's refusing to have sex with him, but she probably feels obligated and has been made to believe his cheating was her fault for not meeting his needs. Poor Anna. I hope someday her siblings that live "normally" will finally get through to her.
Apparently they are expecting their fifth baby and far enough along to know it is a boy!
http://www.foxnews.com/entertainment/2017/03/18/josh-and-anna-duggar-are-expecting-baby-no-5.html