(please keep reading, it leads to serious problem regarding my mums welfare)
Ive been having ongoing problems with my sister for most of my life. Its a fact: she has issues. Her behavior has swung about resulting in going back and forth between black sheep/golden child status within our family for a long long time.

Her normal behaviors are more manipulative than anything and also lying about situations to get her way.

Let me say first off, this behaviour has landed her some amazingly paid jobs, simply by being able to talk her way through interviews and such, my mum is a solicitor, my sister is in recruitment and has maintained jobs of 50k per annum. Im explaining this now because it puts some of the below issues into perspective.

Things like coming to stay at my mums temorarily to help her out with her daily life - she was having mobility issues due to a tumor on a nerve in her foot. I was around, and I helped where I could, but I was working, in my final year of uni and in and out of hospital so I was relieved and grateful when the pressure was taken off me to juggle these things and look after my mum. Anyway, my mum had an operation and is now fine, but my sister isnt going anywhere - shes taken up permanent residence at my mums house. Issues have involved her moving my mums furniture and belongings around to suit her, and when my mum expresses her dislike for the changes and moves it back to how she likes, shouting arguments ensue. My mum gave her her old car as a temporary stop gap, at one point my sister fails to pay the insurance and blames my mum for "forcing" the car (that she apparently doesnt want) on her hoping she would be guilt-pressured into paying for said insurance. My mum arranges to have the car sold and my sister quickly back peddles and pleads with my mum to allow her to keep it.. Debt collectors bills start arriving (amounting to more than 4k debt) at my mums house, and my mum ends up having to bail her out basically on the grounds that she cant be dealing with these people turning up and repossessing her own belongings.

When I became homeless, my sister stepped in to help me, I have learning difficulties and find paperwork and processes hard to follow so she in a way became an advocate for me. Which is great (I couldnt have done it without help), and when she then turned and said she was having money problems, she didnt ask directly but I said with my first disability check I would help her out as a payment for her help and also because I missed her birthday due to being in psych hospital. I gave her a couple of amount options to guage what she was looking for which basically escalated into me giving her £200 of my first £241 bi-monthly disability checks. Im not rolling in money by any means, but I will often put others financial needs before my own, meaning sometimes Im really skint - but I hate seeing people struggle.

Since I have been more open with her about my learning difficulties so that she can help me with paperwork I have noticed she has found ways to manipulate me using these problems, these manipulations have been growing in frequency and the stories more wild. Making up conversations, or making it seem like we never had conversations that took place. I may have learning difficulties, but that doesnt mean Im dumb. These "conversations" involved either money that I was supposedly going to give her, money that she owed me from previous years (which I wasnt even raising as an issue as I wasnt expecting it back) and other such convos.

So all this aside, this is LITERALLY SCRAPING THE SURFACE of my sisters behavior issues, I feel these are the main points that have led to the current situation, but in reality these types of behaviour have been going back to her teen years. She is still living at my mums 18 months later, she is 33. Her verbal abuse towards my mum has been growing.

Finally, the clincher. During an argument she pushed my mum across the hall and then threatened to push her down the stairs.

My mum has confided in me, Im the only one who knows. I tried to urge her to file it with the police, but she refused. (Ironically my mum is a child protection solicitor) so I find this quite hard to sit back and take, because she of all people knows the importance of stepping out of silence when it comes to these issues.

My sister, since this incident has been trying to contact me with texts and calls to which I have only responded once due to being pressured by my mum to keep in contact with her. It was so much effort just to keep it short and civil, I had so much I wanted to say to her, but my mum told me Im not meant to know what happened and that if I say anything that I may make things worse for her. Its getting uncomfortable, its been over 3 months since we spoke, and Ive given no reason why Ive not spoken so she has no idea how angry I am at her and is continuing her manipulative and verbally abusive behaviour towards my mum. IM SO WORRIED ABOUT MY MUM. I cannot visit, Ive been house bound for quite some time.

I feel like Im stuck between wanting to voice my opinion to my sister, and respecting my mums wishes. Ive always told my mum that I love my sister, I just dont like her very much - but recently this has changed and I feel like I have lost that love for my sister by her actions towards my mum.

In the mean time Ive been trying to explain to my mum, that as a family that went through abuse from my father, each one of us made choices whether to end, or continue this cycle of abuse. Apparently my sister, maybe unaware that she is doing so, has chosen to continue this abusive cycle.

Im not even sure what advice can be given, part of this is just venting because I feel I have to be careful who I say this to incase it gets back to my sister and in doing so upsets my mum. Im not sure how I can keep maintaining this facade towards my sister before she starts to catch on that something isnt right by the fact that Im not speaking to her. - and if I dont say anything about this incident I feel it will be swept under the carpet, which given our family history is an all too familiar pattern.

Ultimately my mums safety is my priority.

I feel so stuck.