@ Diane - I swore off crossing oceans sitting back in the cheap seats about 10-15 years ago, since then, I've always been up front in the nice seats for long, globe-spanning flights.
I have some good news for you: it's very likely you will be provided with complimentary slippers on your flight. What airline are you flying on?
Once you get settled in your seat after boarding, you can stow your shoes - there's sometime a specific, designated bin for them (usually on Asian airlines). You will usually find a set of reasonably comfy slippers (new, unused, sealed in plastic) waiting for you with the amenity kit. If you don't see any, ask a flight attendant if they have some; occasionally some business class amenities are "available on request" but not routinely distributed to all passengers. IME almost all airlines give you slippers in BC (even most of the legacy US airlines, on long/overnight flights).
Personally, I find the slippers that United provides in international business class flights a bit narrow for my feet, but I can make them work. I use them only for the trips to the loo - that's all they're for, they come off once I'm back at my seat.
BTW, be sure to check out all the lavs that are available to you in your business class cabin: some aircraft have a small one and a large one; the larger lavs are more comfy (sometimes with a window, occasionally even with real, fresh cut flowers in a vase).
Enjoy your flight, get some solid sleep on the way over; arrive rested, happy, and ready to hit the ground running. Your business class ticket may have just bought you an additional usable day on your trip. 👍