Hello ladies! I need some advice on how to set boundaries.

When my son was born my in law would try to see him once a week and sometimes wouldn’t even ask me what day she could come she will just be like “I will see y’all tomorrow” well that didn’t last long because she did a lot of things to disrespect me and upset me to the point I would cry when she would leave because I would be so pissed. Me and my SO would have arguments about her but he finally understood where I was coming from and began to have my back. I usually let her see my son once every two weeks and for me that’s too soon to see her but I guess I dont like being mean even though she has disrespected me a lot. It looks like now she wants to try seeing us once a week and I just can’t do it that’s too much seeing her 4 times a month for me. How do I do it where I can have it known or a way I can make it two weeks. She doesn’t text my husband she unfortunately texts me so it makes it more hard for me cause I don’t want to come off as rude but also don’t want to have to see her every week again. Thanks in advance ♥️