DM has a problem with alcohol, it's more of a psychological addiction than a physical one as she can and does go without when It suits her.
I thought she'd had a breakthrough recently when she agreed to see a support service on a regular basis and stop drinking, against my better judgement despite years of emotional abuse I supported her once again, ferrying her to and from appointments. She showed commitment to going and not drinking (or so I was lead to believe) so I welcomed her round in the Christmas period to spend time with the DC, sober. She arrives last night under the influence and says it's because she's been doing so well with her alcohol support counsellor and blew a zero reading on a breathalyser so she wanted to celebrate 
I made her a hot drink then told her she had to leave and not to contact me again because we're done here.
She has disrespected my boundaries too many times, coming here under the influence around my DC when we've strictly agreed no contact whilst in drink.
I never want to see or speak to her again, so my question is AIBU to disown her completely especially over Christmas? She impacts my mood in such a negative way I no longer want to know her.