to think SIL is being selfish??

[fairytalesaretrue]

We visited Oh's family this morning and announced that I was 14pg. Everyone really happy and excited for us.

Sil and mil go into the kitchen to make some tea and I overhear them talking about the pregnancy and sil say "I can't believe it, this is suppose to be my year."

... She is getting married next year (baby is due before the wedding).

Now there has been non-stop talk about the wedding for a long time and I suppose she feels like I've stolen some of the limelight.

Ok so when it was my wedding yes I wanted the day to be about me and possibly OH but the whole year?? Erm ... no.

But she didn't slag off the parents to be, or call anyone names.
She had a quiet chat with her mum about feeling a bit upstaged, that's all.

The OP could choose not to have heard it.
Or she can choose to make it a problem that might otherwise completely go away

SIL might be a spoilt princess, or she might feel that she lives continually in her brother's shadow, how do we know?

Congratulations.

Is she having a child free wedding? if she wasn't before I bet she will now

Yanbu. I think it's sad she's not excited about your kids being of similar ages and growing up together.