Ah MIL's..... mine is quite a piece of work!
my dh is her eldest (of 7) and was almost like a second husband for her, running errands, dropping younger ones off, doing shopping etc
until i came along...... (I was his first gf)
We had been married for 10 days or so and she phoned and said "my washing machine's broken" (no Hi, how are you or anything)
I said "oh no, would you like me to do some washing for you?"
she said " No, I want Andrew to buy me a new washing machine"
I said "we can't afford it" ( a bit gobsmacked)
she said "well he would of done until he married you", and hung up!
fast forward a few years, and they were setting up a business with 2 of his brothers. Wanted him to buy into the partnership. By this point we had 3 dc, and we could see that what they were proposing wasn't going to make enough money to keep 3 families and the parents, so said thanks but no thanks......
Which of course was all my doing (not true)
Ds2 was 11 weeks...... we didn't speak again for about 5 years, until we happened to bump smack bang into her when ds3 was 6 months.
And in that time, she never once sent one of the children a birthday card or had any contact whatsoever..... all while living less than an hour away!
Reluctantly I instigated contact, as ds1 who was 10 by now had a lot of questions, and I never wanted him to blame me for the situation. I figured he was old enough to make his own mind up about the situation.
Now we have very sporadic contact, i.e we talk at family weddings,parties and funerals..... and FIL (who isn't quite as bad) only ever rings up if he wants something 
it is sad as they are not old, and are young enough to enjoy the children, but then they have about 17 grandchildren anyway including mine, so no great loss I suppose 
she has never helped with childcare or even had one of the dc for an afternoon or anything......... but tbh I have never asked her, though I think she would say no!
We have been married for 15 years and together for 18 now, so don't think things will change!
When it comes to my parents, they are still together, but neither of them want to be! 
I love my dad and see him loads, and he is always round to help if I need it. I have always had a much more difficult relationship with my mum. She is less than pleased that I am having another dc. In fact she has not mentioned the fact to me once in conversation. And if I bring it up she changes the subject! And last time dd1 saw her she gave her a lecture about not ending up like me!!!!
sorry for the mammoth post 