I'm worried that my ex-husband and his wife are starting to cross boundaries with my family
Why do you think that they are crossing boundaries?
Well, my ex-husband and his wife tried to be really good with me and all, but I just can't accept them into my life.
It's understandable that you would want your ex-husband and his new wife to not be close to your family. It's important for an ex to respect the boundaries that you have once the relationship is over.
I just want my ex-husband to feel a bit sad.
It's normal to hope people miss you a little bit, but you really shouldn't want him to feel sad. You'll have an easier time moving on yourself if you just wish the best for him. It's time to move on.