Well, before anything else I would like to say that is is pretty amazing that you have been looking after your mum for so long,…I take my hat off to you.
Secondly, I am probably not the kind of person you were hoping to hear from , being a wife rather than a daughter or son about to move out. But I have a son ( aged 25) who has lived at home since graduating, and he is trying to leave home, having only recently thought that he would take on more responsibility for caring for his dad.
In my opinion, which is of course subjective, I think that young people have their own lives to lead and should lead them . That doesn’t mean not helping a parent, but it does mean not being their main carer, unless of course you decide that that is what you actually want to do at this stage, and for some it may be . If you were not around, an alternative would have to be found. It can be hard to decide , esp if you are wrestling with what you feel you “ought” to do as opposed to what you want to do.
You might find Hugh Marriott’s Book, The Selfish Pig’s guide to caring” a helpful source of advice…it is mostly written from the point of view of a partner who is the carer, but he is completely aware that lots of other people, including young people are also carers and has a chapter for the latter in particular.
Both my and my husband’s relationship with our son has suffered due to the situation we are in and the effects of the stress that it causes. It is no one’s fault and all too easy for an outsider to say that one just has to control one’s anger or irritation or frustrations or whatever, but as I am sure you know it is not that easy. Relationships matter, and can be damaged in a way that can be avoided, but often is not , which is partly why moving out. Is the right thing to do.
Perhaps you could do it in a staged way ( stay overnight or two or three nights with friends or relatives ) so that your Mum has time to get used to new arrangements and you can be sure that she is getting the quality of care that she needs, or at least good enough care.
I don’t know the detail of your mum’s Parkinson’s or what she needs by way of care, but it can take time to find the “ right” carers, and I would strongly suggest that you meet prospective carers before they start doing the job . I imagine that most of them will do the practical stuff well enough, but it is the personality side of things that can be hard to get right. Don’t be afraid to ask to meet others in order to find the right person for your mum ( and for you if I am honest)
Much as you are wanting/ planning to move out, I suspect you will find it hard, whether due to ( misplaced ) guilt, or concern about how your Mum is doing when you are not there. I only say that to pre warn you as to what might lie ahead. I can imagine that you might find the adjustment to a new kind of life as challenging as your mum might , or perhaps even more so.
A final thought before I go, is whether you might find it helpful to talk to a third party, with your mum, about how you are both feeling about your impending move. It might enable you both to express thoughts and feelings which are hard to say when it is just the two of you, and could help set you both up for a smoother transition to a new kind of relationship, and one that is more mother/daughter, than cared for/ carer.
Wishing you well with how it all goes, and hoping that you take great pride in all you have done and will continue to do, one way or the other, for your mum ,