I believe the OP said that the SIL tried once during a busy time at work. She is now not returning phone calls or text messages. I would call that a bit selfish and pouting - not the way the OP is describing it as I feel that is a bit over the top without any sort of back story - but SIL needs to at least text back now with the OP's DH apologizing (a lot) for not getting back sooner.
This is what I was trying to get across. She called once, knowing full well when he works, left no message, and hasn't responded to any of DH's subsequent calls/texts/emails (yes, he had called her multiple times). She texted him the same time with this exact message "Hey, why don't you call me more often?" So it wasn't exactly like she was saying "Call me, I have important news to tell you."

This is typical of SIL though, she tends to be very cryptic.
Also, the main reason I was saying "nasty things" isn't due to the fact that she didn't contact DH and I...It's more of the load of trouble I'm anticipating between her and MIL. It's already pretty obvious that she is going to use her pregnancy/baby as a bargaining chip with MIL. MIL is incredibly generous and selfless, while SIL is...well, like I described, the opposite. (I posted about their rel
ationship before where MIL paid $3k to fix SIL's car, who responded by calling her a horrible mother.) MIL really wants grandchildren and SIL is already using that fact to try to get money out of her.

Not to mention we're both very concerned about the choices SIL is about to make. She just turned 20 recently and still hasn't learned what being an adult really means. The father of her baby is her boyfriend who she's been seeing for 3 months and went through a divorce only a few months before they started da
ting. SIL plans to quit her job, move across the country to marry the guy and be a stay at home mom. MIL is very worried because it's almost a mirror image of what happened when she got pregnant with DH and it resulted in a long, nasty divorce resulting in her living in a woman's shelter because she had no way to support herself. SIL thinks this is her Cinderella story and having a baby is going to seal the deal, so we're all really worried.