ITS LONG!

Hi all, so I’ve been having trouble with my MIL for nearly 2 years now with boundaries and rules. My partner told her if she didn’t follow the rules she wouldn’t be seeing the children, yet she still continued to disrespect rules and not little rules neither I couldn’t post even half of it because it would be far too long but one problem was she asked for my daughter to go for a sleepover and we both said no and she questioned why, and it’s because she’s ignoring my rules. My son was born at 32 weeks and we were staying with him for the first time (1 week after he was born) because there wasn’t any rooms for us in NICU, they were looking after my 1 year old daughter and she asked to take her to her house for a sleepover and both of us said no because I don’t know the area they are from that well and it’s 2 hrs drive from us. Fast forward my partner FaceTimed his mum and my child was at their house for a sleepover after being told no and to keep her at home, she refused to bring her home, what was meant to be a happy moment for Bonding with my son turned into a nightmare full of arguments because I wanted my child at home. I gave them another chance and set my rules out and she still disrespected them, she had been chewing and liking my child’s food which is a big no no for me, I don’t even do that. I sent her a message as nice as I could after she asked for a sleepover and I said no and got questioned why, she asked to come down but I was busy and she also questioned why bear in mind she’s down once a week from 11am -6/7pm. It’s exhausting. I sent her a text saying she couldn’t have my daughter for a sleepover because she is still disrespecting my rules, she text my partner saying she’s absolutely heartbroken because I asked her to follow rules. She didn’t text me back so I text her again saying I don’t understand why she’s heartbroken because she’s had lots of chances and all I said was I’d appreciate it if she followed my rules. So I’ve told her not to contact me until I feel ready again. She turned up at my door step today and I was away with the children and my partner but I’d feel terrible if my one year old seen her then saw that she wasn’t coming in. Me and my partner have had numerous arguments over her and it’s not just petty things it’s safety concerns. Am I being the bad person I’m not allowing her to walk over me and how do I deal with this situation. It’s taking a toll on our relationship and tbh I can see her breaking us up.