Hi jcaztle and welcome to the forum. My first ileostomy was a bit of a surprise like Nyx's. The surgeon said I may get one but of course I thought no that won't happen to me. Well it did and it was a shock but its amazing how quickly you do adjust to it and get over the ickiness factor etc. My second ileo was planned and I got it Nov 23 last year.
Firstly, yes there is a fair bit of pain post op but its only really bad for a day and they will give you lots of drugs to take the edge off so enjoy them while you can.
Ileostomys can be a real nuisance for the first couple of months while you get used to what products suit you, and until the output settles down and hopefully becomes less liquid. There are lots of threads in this stoma subforum that will give you more information.
It is hard emotionally at first, but you will come to grips with it and we will all be here to offer you support and answer any questions you have. So don't hesitate to ask anything, there are no silly questions here.
I think you asked about going to the bathroom? The bag that will cover your stoma will slowly fill up with the output (poo) and when It gets about hald full then its time to empty it. The nurses will do this for you the first couple of days and the stoma nurse will teach you how to do it and also how to change the bag and baseplate.
Some people shower without the bag on. My ileo is very active so I shower with the bag on. You can also swim and have a bath with them. They stick on pretty well.
The stoma nurse will give you heaps of information and teach you everything you need to know but thee will always be stuff they don't cover and thats where we will all be able to help you.
Mentally, I think the only way to deal with it is to accept that it is necessary and that it is helping your bottom heal which is a good thing. Think of all the horrible things you put up with now and that they will be gone. Read all the threads on here to learn as much as you can. The products available nowadays are pretty good so no-one will know you have a stoma unless you tell them. i don't work so I can't help you with that but lots of people here do with no trouble.
Anything else just ask me. I've got a bit of brain fog today so sorry if this answer seems disjointed.
And all the best for Friday. Let us now how the operation goes and how you are coping. If you post in this stoma sub forum there are a lot of us who will see and help you.