First birthday drama

So I don't like my partner's nan. When he told her I was pregnant she said "well you know she just got pregnant to stay in this country right?" (Because I'm an immigrant... yeah). Every time she comes over she makes comments about the house or baby that puts us down, but because we're both polite we never say anything to not cause an argument. But yesterday she came over, said a bunch of buckshot comments as usual and as she was leaving she went "that garden... oh my god. Oh god that will be some hard work" because it needs weeding a bit but like ???? It's been bloody snowing and raining I'm not going to weed in those conditions. But the point is, it's super rude! I'd never go to her house and say shit like that. She's always super condescending towards my partner as well so he's never liked her. Now I wanted to throw a party for my LO, nothing crazy just a bbq and some cake in our garden, but after yesterday I've had enough of her so I told my partner I don't really want to do it anymore. I'd get cake for us and then we can take LO to the zoo or something. Now he wasn't happy about this and said that we have to do something for the family to celebrate LO as they'll want to see him and he can't not invite his nan. How do I navigate this? She's never visited my son, not since he was a newborn anyway, so I doubt she cares. I just don't want her making comments about my house or my baby because I know I will blow up, and I don't want to make or awkward for everyone or ruin my sons birthday.