To ask how to help this friend, if at all?

[NotReallySureHow]

NC as I don't know if my friend is on here...

Basically, I have a friend who has been in my life for 25 years. She has 3 kids with her partner. Now, my question is how to help her because:

Her partner is really nasty to her in front of me. And she has ongoing issues of her own as a result. It's a long story so I've had to simply, not meaning to drip feed. She drinks too much but is a functioning alcohol maybe as she never appears drunk? She has v low self esteem and always has, and as a result of stress/life/her 'D'H and drinking has gained from a size 6 to a side 24 and is deeply unhealthy now/she has become a bit of a recluse in her life and isn't able to do anything nice for herself.
Her DH is nasty to her, has called her stupid, ugly etc in front of me. They've been together 15 years and I told her at the start what I thought of him, and then about 5 years in when he was particularly nasty to her in front of me I tried to de escalate the situation but also stand up for her....but I've not intervened since as she went quiet with me.
I'm like an auntie to the kids and used to babysit a bit but now have 1 of my own, 2 jobs, and a degree that is taking up a lot of my time.

I don't know how to help her. Part of me thinks I need to butt out and stop assuming she is unhappy but the other part knows her well and she just seems so deflated and dejected. She can hardly walk due to the weight, I've tried to help her with fitness and confidence but suggesting casually that I come by after bed time for a girls eve and we do nice healthy meals (I'd cook if she wanted!) and we go for a walk after bedtime but her partner gets in the way. I'm worried she will take herself into an early death either from stress/drink/weight related issues.

I'm a bit all over the place with it really as I am actually worried about her.

Simplify**, not simply 🙄

So many typos, sorry guys, I'm tired

I think I would do this. Tell her you love her, that your door is always open, that you will always be there if she needs you.

However, you cannot listen to her partner insult and belittle her. She can choose if this means: you can challenge him; you can simply leave when he does it; you can meet alone; you can be at a distance for now. Give her the power within your boundaries. I simply couldn't listen to someone being abused and tacitly agree by saying nothing.

I did similar with a friend and she eventually left him (for my sofa). But she could equally have stayed.

@MrsTerryPratchett I so want to tell her, but she's quite gentle emotionally (despite being an incredibly strong person) and so I wouldn't want to upset her. She doesn't acknowledge when he's nasty to her and I don't know what's going on in her mind? She keeps inviting us to couples events and double dates but my DH refuses point blank to engage as he hates the partner for how nasty he is to her, also he believes a lot of strange conspiracy theories so he's also hard work to be around.

Every time there's an event such as vday, Mother's Day, her bday etc I tell her she's a wonderful person and I will always be there for her. I hope she believes it. I've never given her reason not to (I hope!)

I'm planning her 40th soon and want to give her a calm but fun girly evening where she gets to just chill out a bit. But she's trying to put me off planning it and I wonder if it's him..

Forget about her being upset in the moment when you tell her you notice that her partner is abusive to her and that you can see it's affecting her. In the long run it will do her good.

Being a witness to abuse and not even acknowledging it is basically saying you are OK with it. Of course it's not your responsibility to stop it but I think it is within your role as a friend to talk to your friend about it. Your friend needs to be seen.