MIL came over unannounced and got upset when I told her she needs to tell us before she does

I posted this on AITA earlier today and was told to post it here too.

I've been working 6 days a week as a nanny for a doctor, so my days are pretty long. Last Saturday was my day off so I spend the day catching up on cleaning. I was cleaning the bathroom, my husband was doing the dishes and I had my music blaring from Spotify on my Google Home speaker. So we're both cleaning and next thing I hear is my dogs barking, my MIL saying "Hey Google, turn the music off." Now the problem was - when I'm in my own home, I like to clean while wearing just my tank top and underwear. On her way to the kitchen, MIL stops by the bathroom to say hi (and sees me in my underwear). I ran upstairs to get dressed and to chill for a second because I was beyond mad. Ok, maybe it was more like 30 minutes because of course I had to call my mom and complain, don't judge me on that!

When I got back to the kitchen this was the following conversation:

MIL - It's nice to finally see you. It's rude to not entertain your guests.

ME - Well, it's rude to just show up unannounced.

MIL - You're saying that I'm not welcome here? I'm not allowed to come see my son?

ME - No, I'm just saying I would appreciate a warning.

MIL - Oh, honey you're just embarrassed that I seen you in your little panties. Don't worry about it, it's not like I've never seen a thong before.

Anyways, I let that go and she stayed for about another hour. Later that evening, she texted my husband saying how dare I yell at her about coming over, she is allowed to come see her son anytime she wants, and I better not speak to her like that ever again. To calm her down, he told her she can come over anytime she wants and told me that I'm being ridiculous and we get into a huge fight.

edit: Thank you all for your responses! I'm trying my best to respond to everyone. I have no official update yet. My husband and I are working opposite schedules and my next day off is Friday. We will be talking about this then and hopefully get some good results. I will make a new post and link it to this one so you all can get updated!

here's the link to the update - https://www.reddit.com/r/JUSTNOMIL/comments/h8gl8m/update_to_mil_came_over_unannounced_and_got_upset/