AIBU to not invite friends child to a birthday?

[Highflow]

I’ve been good friends with a school mum since we met at the school 4 years ago. Our children of similar ages have ‘got along’ together, but mainly just because of our friendship. They’ve always gone to each other’s birthday parties.
This year DS, 10 doesn’t want to invite her son. They’ve definitely grown apart in recent months and friends DS, 9 has been acting very immature and getting into trouble at school, swearing, throwing bottles at other kids after school.
DS has chosen 6 of his closest friends, so it’s not a big do so this other boys behaviour will really stand out.
I’m in a really awkward situation

No you're not. It's not your party, your DS is fully old enough to choose his own friends. Back off, leave them too it.

YANBU

I am in a similar situation this year although our children are younger (6-7). My child doesn't want to invite the other child because they don't get along anymore, so we won't be doing so. If my friend asks, I'm just going to say that my child wanted a small party at home and so only invited 4 friends (which is all true).

Give her a heads up that this year your son is having a very small gathering of only his closest friends.

It is your son's choice to make, but letting her know is the polite thing to do.

If she takes offence, that's on her.

To add a bit more context I got the sense that at friends DS birthday my DS was only invited by his mum.
I know it’s up to my DS and I need to let him choose, I just know she’ll really take offence at this rather than actually thinking about if our boys actually get on

@KangSaeByeok

No you're not. It's not your party, your DS is fully old enough to choose his own friends. Back off, leave them too it.

Absolutely this!

@Highflow

To add a bit more context I got the sense that at friends DS birthday my DS was only invited by his mum. I know it’s up to my DS and I need to let him choose, I just know she’ll really take offence at this rather than actually thinking about if our boys actually get on

Well that is on her.

Your ds has long passed the age when anyone but he should be completely choosing who he invites to his own birthday party

I would second what the poster above says, you don't have to invite him, your son has given you a list but give her the heads first. 'He made the list and just wanted to let you know ..... They seem to have drifted apart' etc.