DH and I have been together 5 years, married for 3 with and 11 month old DS. DH's mum has always been a nasty cow to me, and I simply do not understand it as I have never done anything to her and have always been loving and faithful to my DH. She has another DIL who she is perfectly fine with, though I suspect it may be as she has been friends with DIL's mother since their children were babies. She got particularly horrible after I had DS, and has even suggested to my DH in confidence that he should get a DNA test done on our baby because she thinks he looks mixed race and we are both white! It is absolutely ridiculous, I've not slept with anyone other than DH since we got together and I can't believe that she thinks I'm such a slapper (yes, she has said it). DH unfortunately always defends her, he doesn't agree with her claims about me and DS but he has a lot of guilt over her. He says he was extremely vile to her as a teenager and that contributed to her attempting suicide when he was 16, so he does not want to argue with her and spent most of his adulthood so far trying to have a great relationship with her to make up for it. The only thing he has done in response to her snipes at me was "have a quiet word" with her which doesn't change anything.
I am reaching my wits ends and I just want to completely withdraw from his family but he insists that I attend family events with him and DS. Last Saturday we were at Pizza Express with me, DH, our DS, MIL, her other DS and other DS's wife and daughter for the daughter's 8th birthday. She spent the whole meal complaining about DS's nappy. About half an hour in she commented about how I need to go to the bathroom and change him because it was putting her off her food. I knew for a fact that his nappy was clean, he'd been sat on my knee the whole time and I would have felt something, and I would have been able to smell it which I couldn't. I reluctantly took DS to the bathroom, knowing full well that he would be clean (he was), changed his nappy and took him back to the table. 10 minutes later, she commented again and even had the nerve to say "What on earth are you feeding that baby?". So, I took him to the bathroom again and hid in there for a couple of minutes, not even bothering to change him as I knew he was still clean. I came back, acting as if I'd changed him again hoping she'd stop. Of course she did it again while we were eating dessert, and began passively aggressively telling me that I need to change his diet. I rushed to the bathroom and cried as it was clear she was winding me up. She knew full well he was clean and even the rest of the family kept telling her that they couldn't smell anything, but she just had to take any opportunity to get at me.
Me and DH left early, because he could see I was distressed. We didn't hear from any of the family until yesterday, when his mother got in contact to give a half hearted apology (she does this often, it's never genuine) and to ask us to go to the Netherland's with her for a week around Christmas with her other DC's in a holiday cottage. DH is annoyed with me as I don't want to go, and has been quite snappy with me telling me that we are both as bad as each other. Should I really be expected to spend a week around this horrible woman and have her call me a shit mother 24/7?