Makes no difference to me but I do wonder how you survive in the real world out there? I own a shop and I'd be scuppered if I refused to open the door to strangers, let alone my own relatives grin. Do some of you have the full moat, drawbridge and boiling oil combinations ready to foil unwanted visitors, well that's all visitors isn't it?
There are a lot of stupid comments on this thread, but this is the most stupid. I presume you own a shop because you get something out of it, i.e., money. I presume your expectations when you open your shop door is that you will get polite customers, who will be there to buy something (thus benefitting you greatly), and then leaving in a timely fashion. Now imagine someone barging into your shop just as you were about to close for the day. Imagine them refusing to leave because they are just browsing, and shouldn't you be grateful for a customer? Now imagine them breaking or consuming some of your goods; imagine them haranguing you for the goods that you sell. What have you got in the stock room, can they have a look? Why not? You are hurting their feelings, they are a customer, they are here to help your business, what's wrong with you. Imagine them demanding to use your loo, your kitchen, your private space. Do you? Or do you have some boundaries?
Now apply a metaphor of that situation to a very private person who's personal time is their "shop". They are open for business when they are ready and willing to be open. However, they are being barged into outside of their mental "opening hours". Peace of mind/free time/alone time swallowed up by someone not welcome, goods (their time) consumed, stockroom (their boundaries) plundered, facilities (both real and metaphorical in the mental health sense) used up. And, unlike you and your shop, they get nothing to show for it.
It never fails to amaze me that people on this site can't put themselves into the shoes of someone who does not have a happy history with their parents and at best has an uneasy present relationship. This does not mean that the OP or anyone else in a similar situation can't survive in the real world. She's about to go out to work, which I would say is ample proof that she is just fine.
OP, you maybe didn't handle it in the best possible way, but you are not unreasonable to turn your father away. Obviously there's some history here. Define your boundaries and stick to them. Don't be guilted by the "he might die and you'll regret it" brigade. He might also live to 100 and spend it all ruining yours. Do what's right for your own mental health.