Been with DH 17 years. I have tried so hard with his parents right from the start - their hearts are in the right places but they are hard work (acknowledged by him, his siblings, and anyone else I know who have met them!). Extremely old-fashioned and with a very narrow world view. I've always known they think I'm weird but I've had it confirmed as MIL has apparently 'never met anyone in sixty years' who thinks like me 
This is related to the very small world she lives in - I'm not weird, I'm just not a Tory-voting Stepford wife who wants to always stay 'on English soil' and not ever go abroad.
We have had a few blazing arguments, the last of which followed a now-predictable pattern: she loudly criticised something we'd done (she thinks I tell DH what to do - I don't), I tried to explain our point of view, she pretended to listen but carried on saying how ridiculous it was, I asked if we could change the subject, she carried on ranting, I walked out and she followed me round the house continuing to rant. I eventually yelled at her to leave me alone, burst into tears and left the house. Since then I've tried to avoid them (FIL not as bad but asks a million questions about everything and won't ever stop and you feel backed into a corner all the time). They also think I'm weird as I don't cope well with big gatherings, which they have a lot of and can't understand why I don't want to spend a week going on holiday with twelve or so of them from DH's family, and I struggle with eye contact (I'm autistic) which MIL thinks is 'very strange' and hasn't come across before
For my own sanity I need to stay away. I have told DH I will never have a problem with him going or taking the kids to visit. When they come here I have stayed in another claiming headache or something or made sure I'm out. I make exceptions for things like DH's or the kids' birthdays but it's about all I can cope with after nearly two decades of criticism. I will never be good enough for them, I will always be thought of as the odd girl that DH married, and they will always treat me like I'm a naive teenager (I suspect this is because we were teenagers when we got together because they treat SIL differently. Also DH is like the 'black sheep' of the family because he was challenging as a child, and the sun shines out of his siblings' behinds, so it's not a great combination!).
I suppose I'm asking how we should go forward. I just can't put myself in a situation where I'm subject to frequent criticism and / or my opinions being humoured, and my parenting style questioned. It's just had a cumulative effect over the years which has resulted in a situation where I probably react more to little things because it's built up over a long period of time. I'm not sure how to deal with things - DH doesn't want to tell his parents the truth but I think it would just be clearer if he just told them (and might actually make MIL see just how much she has upset me). I've tried everything, I've even written to explain how I feel, but I feel like I'm done now and I don't want to subject myself to any more of it.