Surviving Secondary Infertility?

Yesterday I found out that my friend B is going in today for a D&C. The baby stopped growing at 10 weeks. This is her fourth pregnancy, and she has one child.

I just feel so sad for her. I really thought the miscarriage/D&C/loathing-her-body/frozen-smile-when-other-people-announce-their-pregnancies stage of her life was over. She should have been able to relax as soon as she hit 8 weeks.

And my other friend's friend, C, just lost a baby at 10 weeks, too. She got pregnant easily with her 3-year-old, and had no complications. Then last year she lost a baby at 20 weeks. Genetic problems--a fluke. So why is she back on the roller coaster again with this fresh loss?

For those of you who have been there in secondary infertility hell, how did you make it through? For those of you still in it, what's the worst part? How do you maintain hope?