I don’t know why but your post really struck a chord with me so I wanted to take the time to reply.
My mum was/is in a similar situation to you. Her youngest brother (my uncle) has Bipolar and growing up it was horrible to see the way he would sometimes treat my mum. I distinctly remember one holiday when she constantly got abusive texts, phone calls, voice mails. I can’t remember what it was about but it was either not my mum’s fault, or, if it was, it certainly didn’t justift his behaviour.
Whenever the phone would ring and I would see his number I used to dread answering it because you would never know what mood he was in. I can imagine your sister is probably like this – when she is in a good mood she can be fantastic to be around but when she isn’t then she can be vile and horrible and everyone knows it, there is no in between.
I don’t know if my uncle had a problem with alcohol in the same way your sister does and he definitely wasn’t violent from what I knew (he did tend to self harm instead). However, we (my sisters and I) did not see him very often and usually at our house. I think he knew and respected how he should behave there so we never really saw his “bad side”, ok he would sometimes be down but never extreme.
You mentioned that your mum wants you to take over your sister’s finances once she is no longer around. My mum and their other brother do this for my uncle (not sure if it is ALL his finances but certainly his spending money) because he just cannot be trusted with money. If you gave him £40 and told him he had to make it last a month you can guarantee it would be gone in a day. He just does not understand about budgeting. I don’t know if it’s the disorder, the fact that he was probably never taught about looking after money, or that he is just an habitual spender because there are plenty of people like that.
I certainly don’t think your mum is helping matters by looking after your sister’s finances. I think if anything she should be trying to help your sister with her finances and, even then, if she struggles, then maybe some kind of support would be useful.
As the niece of an uncle with a mental health disorder I do feel it is important that you allow your child to make up their own mind about your sister. My parents always showed love and kindness to my uncle but it was from a distance. They never spoke badly about him in front of me and my sisters and, over time, we were able to form our own personal oppinions on him. I don’t know how my sisters feel towards him but in terms of me: I love him because he is my uncle and I am always friendly and respectful but I am not close to him.
On the other hand take my cousin whose mum is another sister in this family. My aunt does not/did not like my uncle and her oppinion on him was clearly shown to my cousin and, as a result, I don’t think my cousin likes him very much. If there are any negative feelings towards your sister then I would encourage you and your husband to keep them to yourselves – you don’t want your child to associate all people with mental health issues in a negative light.
I do agree with your husband that inviting her to the party would be a bad idea (unless you choose to have a no alcohol gathering) as she has shown she cannot be trusted in those situations – I definitely wouldn’t excuse her behaviour. At the end of the day I don’t think it is the alcohol she is drinking that is the problem but the amount she is drinking. No one but her is pouring all that alocohol down her neck, she is doing that all to herself.
I think it would be better, as others have said, to arrange to see her in a smaller person environment where the need for alcohol isn’t there. I think it’s important that you remain some sort of relationship with your sister because probably you are the only good thing in her life (even if she doesn’t want to see it). You and your husband are in an ideal place to show her that not all relationships have to be abusive and she too could be with someone good.
I think in terms of seeing your child I wouldn’t do it at your house but in a public place. If your sister does start to get abusive then it will be easier for you to leave than for you to kick her out of your house. If your sister wishes to have a relationship with her niece/nephew then it will be on your terms.
Setting boundaries (not just with your child but with you as well) is vital. She needs to know that while some of her behaviour might be explainable by her issues that doesn’t mean they are excusable. If she has done or said something wrong that has hurt your feelings then you need to tell her. She may not like it and get abusive but she needs to learn. By The Way, I would love to know what happens at work if someone says she has done something wrong – does she accept it and listen or does she get angry with them too?
I think if your sister wants to have a proper relationship with you and your family then she needs to accept that she needs to make changes in her life. Your mum should not force you to give in to her like she has done.