You poor bugger - I completely get what you mean.

I can't stand my In-laws and about 6 weeks ago I had 3 years worth of anger and one very pregnant/hormonal moment and let them rip with everything I'd thought of them.

If that wasn't enough, I followed up with a 7 page letter nailing the point home.

Suffice to say I haven't heard from them since and am very pleased about it (luckily my DH used the think the sun shone out of his parents behinds and has since seen the light)

Take a deep breath, calmly explain things to your DP and then if it doesn't work, the minute your MIL says something out of line, firmly tell her you won't have their rudeness