How do I handle my mom repeatedly ignoring a boundary with my newborn?

Heads up, english not the greatest. I’m looking for advice on how to handle a situation with my mom, because I don’t know how to trust her.
I came home from the hospital three weeks ago with my three-day-old baby. Before he was born, I printed out a list of rules for my parents and brother to follow when entering his room, since we currently live with my parents, very common here in eastern european cultures. My rules are nothing crazy, basic hygiene, no perfume, washing hands, and no kissing the baby.
I’m particularly worried about newborn viruses, especially HSV. I know a lot of people/cultures consider the no-kissing rule excessive, but it’s something I feel strongly about while he’s so young. I know infected people are contagious only 3 days out of the month, but idc, I don’t kiss him myself, and I’m very careful about where people touch him (mouth, hands). I know he won’t remember being kissed as a newborn, right now he seems to care much more about being held and skin-to-skin contact.
My mom kissed him during his first week home.
I immediately reminded her about the rule, and she told me I was being too strict, that she doesn’t have any diseases, and that I am overreacting but I know my brother had HSV a few years ago. In our family/culture, sharing drinks or drinking from the same cup is completely normal, so I know we all have it, it might just be dormant.
I told her that this was the one rule I really couldn't bend because it was about his health.
Since then, I've caught her kissing him several more times. Every time, I've told her to stop. Her response has been that she “forgot”, he’e too cute.
When i tell her, she speaks to my baby, who obviously doesn’t understand anything yet, that I'm being too strict and that I have too many rules. She either says it so that I can hear her or to set grounds for undermining my authority in the future for being to strict and that he can run to her when he wants to break the rules.
Today she went to work and my dad told me that she's upset with me. Apparently she feels hurt by the situation as when she came home said hi in a very angry voice and dismissive..
I'm conflicted.
I don't expect my mom to be happy about my rules. I don't expect her to agree with me or even think I'm making reasonable decisions. She's allowed to think what she pleases.
But I do expect her to respect the boundary once I've clearly explained it, even if i live in her house, he’s not her property.
What makes me uncomfortable is that I've repeatedly told her not to do something, she continues doing it, and then says she forgot. Now she's upset that I have trouble trusting her alone with him anymore.. and it’s sad because i wish i could leave him with someone else other than my husband, who thank God helped me so much during this period
Somehow I don't really feel guilty that she's upset. At some point during pregnancy, I think my people-pleasing just disappeared. I don't want to hurt my mom, but I also don't feel like I should apologize for having a boundary concerning my newborn.
So I'm wondering:
How would you handle this?