OMG, yes! I could have written this when my father died (well, we didn't run a business together, and I don't have children, but otherwise...) The evening he died, after we left the hospital, my mother and sister and BiL were going back home. I'd have liked to go with them, but sister & BiL just wanted each other, and my mother said she didn't want anyone around, so I had to be on my own whether I wanted it or not (my local friends were away, as it was summer.) My needs and feelings were irrelevant.
Never really dealt with it, to be honest. I went travelling some months after my father died (I'd started planning it before we knew he was ill, and he was adamant I should go), and then got a job 2 hours away. I'm not sure my sister had it that much easier, really, because being still local to Mum, she got all the phone calls asking her to just pop over to run a little errand, do a little favour and so on. I spoke to her about every 2 weeks or so, and saw her two or three times a year. It was easier at a distance (but I didn't have the issue of a shared business to deal with.)
When my father died, it was a massive, gaping hole in my life. When my mother died - well, I miss lots of things, but there are other parts of her personality I don't miss, and my life is easier without her always emotionally undermining me and everything. It's been a very different grieving process.
So I'm sorry I have no useful advice, just sympathy, because I have been somewhere similar.