What a terrible time you have had. You sure didn't need a Parkinsons diagnosis. I may be on my own here, but I think what you've been through already is far more scary than Parkinsons, and if you're partner cared for you through that, then Parkinsons shouldn't be too bad. I've been diagnosed for four years now, at the age of 50, and I consider myself nowhere near requiring a 'carer'. I keep active, I look after my granddaughter two mornings a week, I take enough medication to keep me moving, no more and no less. I know I will get progressively worse, but I'm not going to give in easily.
What a blow for you reading that one of you're cancer drugs may have caused you're Parkinsons, especially when there is so much in the media about a cancer drug actually improving the quality of lives of some sufferers. I know lots of people hate the phrase 'stay positive', but, for me it works.
I note that you are waiting to discuss medication options with you're GP. I know many gp's are excellent, but they are general practitioners, I would chat about medication to you're neurologist, maybe in conjunction with you're oncologist, to make sure you get the best treatment.
I hope all works out for you