Am I overreacting?

AmKaSaw

SIL, who is 12 years older than DH and considers herself the head of the family, just sent us a text yesterday saying she bought us a really nice stroller.  She's also bought a few other things...

 I made it pretty clear to my family that I don't want anything for the baby yet, not until we find out the gender and I'm out of the "danger zone."   DH called to see what was up with the stroller, and she started talking about cribs!  

He immediately told her no, that my parents are buying the furniture, and she seemed irritated by that.

I'm kind of pissed that she would buy an expensive stroller without even asking us. It feels so invasive! I also kind of feel like if his family is butting in this much already...it's just the start.   

I've got kind of a "nip this in the bud" attitude towards this, but I also don't want to cause waves.  Esp. since his family is pretty sensitive and tends to be dramatic about things.  Lots of gossip and easily hurt feelings.

So what do you think, should I just let it go or should I put my foot down?