Verbally advanced 2 year olds and impending births

My DH has been so stressed and overworked lately that he's had a dose of shingles, poor baby. He's had it before and it tends to reappear when he's run down. Unfortunately, there is nothing to be done for it so he has just had to suffer through. Mind you, he's very good at this - a martyr from way back!

We were on our way to my parents house on Saturday when my younger brother rang to invite himself to see us, so instead he invited himself to our parents as well. Both Mum and Dad are quite sick with colds so it was just meant to be a very quiet weekend, a bit of a pity party really, but all of a sudden Mum had to cater for an extra 2 adults and a 2 year old. Which of course she did fine, because she's another martyr!

I love my brother and his wife, and their daughter is just gorgeous too, but as always my stomach drops and I wonder how I will cope seeing my SIL in all her 7 month pregnant glory. My concern is my wayward emotions, its not that I envy her or hate her for her ability to do what I can't. I just worry that I will cry at an inopportune time or say something terribly bitter or morose, like "Goddamn it, why can't I be 7 months pregnant!" and make everyone uncomfortable. We have not told them about our struggles, although I'm sure that my mother has. We get on really well and I'm positive they would be very supportive (her 2 closest friends are doing IVF, one has 2 kids the other has none as yet) but I just can't seem to find the right time/situation to bring it up.

How do you drop "we've been trying to have a baby together for 5 years and are about to start our 12th attempt" into general conversation? Especially when there is a verbally advanced 2 year old and an impending birth to talk about. Consequently, we didn't tell them and my mother accused us of being quiet, and DH didn't get the relaxing weekend I was hoping for.

As an aside, my SIL had this picture book about a new baby coming into a family. It was terribly disturbing. The family were zebra's, the mother wore a dress but the father only wore a hat (feeding the theory that women should be ashamed of their bodies?). Anyway Mama Zebra goes away and comes back with a baby which has a speech balloon on almost every page of "Whah, whah, whah". Little Boy Zebra wants a cuddle from Mama Zebra but Mama Zebra is too busy feeding, cleaning or otherwise placating New Baby Zebra. Little Boy Zebra gets increasingly distressed throughout the story "Can I have a cuddle now?!" until finally Mama Zebra gives him a cuddle and reads him a bedtime story. My brother and SIL had better hope that their verbally advanced child cannot understand the moral of this story - that once this baby is born she'll be ignored all day until bedtime - or they'll have a mutiny on their hands!