ExMIL....is it me?

[onanotherday]

Just found out Exmil has texted dd to arrange coming to stay as its dd birthday (13). I'm really happy for her to stay as we have no family support but think leaving me out of the loop is bad members at best. ..insulting at worst. I have been treated really badly by ex's family ..he is an alchoholic who has recently been diagnoised with BPD and Bipolar....have had years of hell and he left for ow and i got the brunt of the blame and feel totally alienated and isolated. However I always try to be welcoming and polite. Am I over reacting?

Sounds more like you've been under-reacting - being welcoming and polite to people who blame you for their alcoholic son leaving you for OW?!
It's not appropriate for an adult to ask a child if they (the adult) can come to stay - you're the head of the household, they should be asking you.
However, if you do enjoy this person's visits, call her yourself and say 'I hear you'd like to visit on DD's birthday'...

If your daughter wants to see her then I'd go ahead but let her know that you need to be asked.

If your daughter isn't bothered I'd say "oh dear, no can do you should've asked me".

If she ws one of the ones blaming you I'd try not to encourage a relationship with her & GD tbh.

Think I'd tell her to go jump. Blaming you for the fact your DH was unfaithful no left? Perhaps not someone I'd want as an influence in dc's life.

I wouldn't have her either. She shouldn't be asking your DD whether she can come and stay in YOUR house. I would find that deeply insulting. If she wants to meet up with your DD somewhere else and it's okay with you, that's fine. But nobody invites themselves to my house without my say so. Definitely not a person who has blamed me for ExDH leaving. She has no respect for you whatsoever. Doubt ever will