Meanwhile my husband and two boys waited in the house, with Simon and Garfunkel blasting out, in an attempt to drown out mummy and grandma having a slanging match across her car bonnet.
The reason for this explosion? The night before, we had left her in charge of our children (aged two and six), while my husband and I went on a very rare night out together. We arrived back home at midnight, entered a pitch black house, and heard the sound of both our children sobbing and screaming for someone to go to them.
Grandma, having had a bottle of wine and five jam doughnuts, had gone to bed at the other end of the house. She had shut all the doors and failed to the take the baby monitor with her and was unable to hear a thing.
We might as well have left our children completely on their own and gone out, for all the use she was.
Needless to say, I felt completely let down by her, and was heartbroken that my children had been crying for 'a very long time' and no one had come. And from that moment, I knew that I would never ever be able to trust her again, over anything.
The decision to allow her to babysit for us in the first place hadn't come lightly, but as far as our children's grandparents are concerned, she was our last hope of a night out together.
Numerous incidents have happened in the past that have lead me to be very suspicious of her intentions and actions. Like the time she came to visit us knowing that she had gastroenteritis and tried to conceal it from us, while insisting that my then 18-month-old shared a bowl of ice cream with her. The following day my baby caught the virus and was in bed for over a week. My mother-in-law, who eventually admitted that she was very ill during her visit, showed no concern or remorse whatsoever.
Sadly, the reason she forced herself to come and stay wasn't out of a desire to see her grandchildren and certainly not to give us a break, but to put one over her ex-husband – they have battles about who sees my children the most and she can't miss an opportunity to rub his nose in it.
Speaking of her ex-husband, my father-in-law, unfortunately I do not trust him either – he is a health and safety disaster waiting to happen. The first (and last) time I let him take my children out for an afternoon I heard absolute horror stories from my six-year-old on their return.
Not only had he let my two-year-old stand on a riverbank alone while he went into a shop to get ice-creams, he also let him wander alone across a petrol station forecourt, and then failed to strap the car seat into the car properly.
My husband's parents are not old or doddery, nor do they have mental illnesses. It's just that his mum is thoughtless, irresponsible, incompetent, and untrustworthy, and his dad is about as safety conscious as a drunken sword swallower.
While I fully understand and appreciate the importance of a grandparent's role in their grandchildren's lives, I feel like we have somehow missed out on that whole thing. My kids do indeed adore each of their four grandparents (and under tight supervision they are fine, sort of), but sometimes I do crave the freedom that comes with being able trust them.
Having said that, I trust my own mum one hundred percent; she is a selfless, loving, and amazing lady. However, shortly after my first son was born, she was diagnosed with a debilitating illness, and it completely shook my world. This was never how it was meant to be. Although they are a big part of each other's lives, she doesn't get to enjoy them to the max and have all sorts of adventures with them. It seems so unfair and cruel.
My dad, on the other hand, is fit and well, and completely trustworthy - but living on the other side of Europe with his new Italian family, with children the same age as mine.
So I sometimes feel tinges of envy when I see friends' parents taking a proactive role, picking up their grandchildren from school, having them to stay for the weekend, babysitting, and generally relieving the parents from time to time.
"I call my mum my saviour," says Sarah, mum of three girls. "If she wasn't close by to help out I would have gone completely mad by now."
Jo, another friend of mine has the opposite problem with her in-laws – they are completely over-the-top control freaks and constantly criticise her parenting skills. "My husband's mum is the worst," says Jo. "The last time she came she tried to get me to hoover the sitting room before she would set foot in there." So I understand that other people have a hard time too. But what's so frustrating is that most of my friends have at least one functional grandparent.
We are lacking that support network if we are in need of a break, or if we are ill. We have never spent a night together away from our children, and we are not likely to for the next 16 or so years. I adore my children, but I dream of a break sometimes. Clearly, we need to find some reliable babysitters in the area and a bit of spare cash to pay for them.
All this has made my husband and I resolve that if we ever become grandparents ourselves, we will be the most supremely competent and helpful grandparents that have ever walked this earth. That is, unless our children are so independent that they won't need us...
More on Parentdish: Why we should make the most of grandparents
Are you disappointed by your parents' interest and involvement in your children's lives? Or do your children have a wonderful relationship with their grandparents? Tell us your experiences...