Would you stop hanging out with someone if there kids cry over everything

No, but would probably limit meet ups to a frequency that I could handle.

It’s your sister I wouldn’t be doing that

I would say personally it would depend on if the behaviours we're rubbing off on my child. My sil has three kiddos between 7-11 and they all have appauling behaviour, from swearing to throwing things and general violence if things aren't going their way etc, i've even stood and listen to them tell their mother to die and we have almost completely stopped our 2 year old seeing them after she was coming home telling us to get away from her and pushing and was stomping around copying what she had seen her cousins doing. It took us a few week to correct and stop those behaviours she was copying so now we don't really see them unless at a family meal out etc where they are more likely to behave. It's a shame because my little girl loves her cousins still but you have to prioritise who your little one is being influenced by over the family bond in my opinion

It’s totally understandable to feel frustrated in that situation especially when a child’s behavior affects your own child or your peace of mind. Some emotional outbursts can be normal for a 4 year old. What really matters is how the parent responds and in your case, it sounds like your sister isn’t setting boundaries or teaching emotional regulation, which can make things worse over time. I would say if the behavior is constant, disruptive, or hurtful to your own child and your sister isn’t willing to address it, you’re well within your rights to set boundaries or limit how often you hang out. Protecting your child and your own well-being doesn’t make you harsh it makes you responsible.

Her 4 year old rips things out of my daughters hands and pushes her and my sister does nothing about it