Have you thought about why she is like this? Maybe she's from a family where such responses to her own actions and comments are the order of the day. Perhaps she just doesn't know how to behave around you all. Could be you're a little over-sensitive, or it could be that because her own family speak to each other like this, she thinks yours does too.
My daughter in law and I used to tiptoe around each other like a pair of feral cats, me always wondering whether my remarks were going to upset her. Five years on, however, we get along just great and are more like mates than mother and daughter-in-law. Looking back, I can see how difficult she must have found being among us. We're a somewhat liberal, outspoken and 'loud' family and I can see how easy it would be to feel overwhelmed with us if you're a bit on the shy or quiet side. On the other hand, she is from a fairly conservative Nottinghamshire mining family - lovely people, but with rather stricter values than ours. Now that she's found out we're not going to tut disapproval at some of her more wild behaviour - a side of her that we love - we're all able to get along really well.
Clear the ground. Explain that some of the things she says upset you, and tell her why. Tell her that your family don't talk to each other like that and that you find it hard to accept. Then give her a chance to say why what it is you do and say that upsets her and causes her to make such comments. Try to find some middle ground for your son's sake or you will lose him.