Hi Sussexgirl - i think you were very brave to spend a whole week with your MIL !!!
My MIL was a bit odd at first - she actually invited me around for coffee just to sing the praises of my husbands ex !!(which was so hypocritical because she made their life hell and hardly spoke to her)
As time has gone on and i've totally ignored her sniping we have got to know each other, and now we get on really well.
I think she realises that i work hard and keep the family together and im no push over.
Once when she tried to have a go at my husband about me - he just turned around and said - don't make me choose or you will lose -and she's been fine ever sinse. i think your husband should have a word with them and show his support for you more in a nice way. Hope things improve soon.