Is it disrespectful or I'm over reacting ?!

Hello ladies

This afternoon my brother in law's son who's 8 years old said "shut-up" several times to my face while I was talking to his grandparents (my in laws) I was reeeaaaally upset and told him to respect people who are older than him with a serious tone , so what made me really mad is that my husband said to my face that he's just a child I don't have to over react!!!

I told my husband that he should've said something to him instead of defending him while I was talking to him !!

In my family this is waaay too impolite

Did I over react??

Do you see what the 8year old said as a normal thing and I should've said nothing to him???

Update:

We had a huge fight , because he thinks I'm over reacting!! And let me tell you this about this kid and his brothers they are really spoiled and they do what ever they want , one time they called me an animal (I yelled at them because they pinched my daughter when she was only three months and she started crying so much that she barely could breathe and turned into blue, and guess what?! My husband said that I'm overreacting too. They do this kind of stuff to everyone and no one is disciplining them !!

I'm really feeling sad !!