I'm sorry this is so long! I am married, have 1 DS aged 7. My DH's sister is generally lovely and we get on, and she and her DH live a 3 hour drive from us with their 3 DDs, 1, 3 and 5. My SIL has lately been struggling with her mental health and has recently sought help. I have had my own struggles in the past and I'm pleased to be able to support her.
A couple of weekends ago my SIL and her girls came to visit without her DH, and stayed for a couple of nights. Long story short, it was tough going. My DH was sadly ill in bed so was out of the picture, so it was just me and SIL looking after all the children plus our new puppy. I thought it would be fine, but on the first afternoon my SIL announced she was going for a nap, leaving me to take over supervising the kids and make dinner for us all. The girls were really hard to look after, they were into absolutely everything, making a huge mess and not listening at all. My son was getting quite upset as we had set aside a few things he didn't want them playing with before they arrived and they found them and got into them anyway. When my SIL came down she said that my DS needs to learn to share.
The next morning I came down to find the puppy had had diarrhoea in her crate, so spent a while cleaning up that, and then all the kids arrived downstairs. My DNs were asking to be changed or help with bottom-wiping (which I did), but when the older one was asking for medicine as she felt poorly, I asked her to go and wake up their mum as I wasn't sure what I could give her. She came down again to say her mum had told her she would 'sort it out in the morning'. I just sucked it up and got on with it, gave the kids breakfast and my SIL came down later.
We took the kids out for a walk and pub lunch, and it was a bit stressy but generally fine, although my SIL kept telling my DS to look after the girls, and telling him off when he forgot.
Honestly I was so glad when they left. I spent hours tidying after they had gone, and my DS got upset again looking at the mess they'd made of his things.
Later my SIL messaged to say thanks for having them, and she'd love to meet up again soon, saying perhaps we could go and stay with them so my DS can see how they share!
I'm not sure how to respond. I totally understand my SIL is struggling and I want to be kind. But I don't want to put myself or my DS through that stressful experience again! I do want him to be close with his cousins though. Shall I lay down some rules before meeting again?
Advice appreciated as I genuinely want to handle this well!