We live in a very remote and tight knit community, there's only one other kid in ds's year.
His best friend is in the year above. They've been friends since they were 1 and the family moved here.
The friend in question, let's call her Sally, and I have become very close. There are only 4 of us here that are around the same age. I am friends with some of the younger women also.
Sally and her husband have a drink problem. Don't get me wrong, Dh and I probably drink too much, but I'm talking she's often slurring and staggering by 4pm on a weekday. She's also started drinking in the mornings and picking up from school drunk.
Her husband can get violent when he drinks. Both towards her and their child.
Until now I've wanted to stick around in the dynamic to try to support her. She literally has nobody else here. Her family are 1000s of miles away and she has no friends other than me.
But, she started doing this thing where she'd tell my ds that he could go for a sleep over, play date, trip to the beach etc. She'd ramp him up about how much fun they'd have, he'd come and tell me and I'd always say no. At first because we simply had other plans and I felt 3 was too young for sleepovers and quickly because I know how drunk they both get and no way in hell am I leaving ds in the care of someone that loses all control by 6pm, sometimes earlier.
So of course being a 3 year old, now 4 he'd go mental. She'd have built these things up so much and told him he was going when we said no you can imagine the fallout.
She did it on his birthday because she was drunk, he was sobbing and she kept telling him 'well I want to you come but your Mummy and Daddy won't let you.' DH had to carry him away screaming (as you would bring three and being around a very drunk adult) and I asked her to leave.
The last time she did this, I was going away for the evening. I told her so on the phone. She instantly said 'oh, I'll ask your Dh and ds over for dinner then!' This in itself made me a little 
.
I told her Dh had plans to go away with ds. She got to ds's school 15 minutes early for pick up and told ds he was going to her house! DH turned up and the melt down ensued. DH ended up not going away (getting a kid having a melt down on a boat isn't safe) and was furious.
Anyway, long story short (as it's been a wee bit long already but didn't want to drip feed) Dh messaged her the next day and nicely said he appreciated the invite but next time she wanted ds to do something could she please ask us not tell him.
She rings me and flips out at me and tells me she'll now be excluding ds from everything.
Ds is heartbroken to have lost his best friend. (I'm really thinking it's a good thing, this kid is not being brought up in a way I want ds around. Unlimited access to you tube, has a cupboard full of sweets, fizzy drinks and chocolate that he has unrestricted access to, sexualising him from an early age, no bedtime etc etc. They're a very right wing family (think homosexuality is a sin, women are third class next to dogs etc).
DH is thrilled we no longer have to do any social activities with them. She was always a bit creepy hands on with Dh and her husband like wise with me 
not envy.
She's also quite spiteful to me when she's drunk. She'll make nasty comments about me to Dh or friends.
A couple of people gave since said that they think I'm being cruel as I was her only friend. And she is a sweet and giving person when she doesn't drink. She'll give you the shirt off her back and when I had a miscarriage she was there for me.
Most people have said they just don't want anything to do with her though.
So I feel like I'm turning my back on someone that really needs me. She literally has nobody else. But I can't continue to have ds around this.
Sorry it was long and a bit of verbal diarrhoea, just wondered what others with some outside perspective thought.