It's good to be informed, but try not to worry, it sounds horrific, but it was surprisingly okay for me. I can't comment on a 3rd degree tear, which I understand can be difficult because in some cases a bit of reconstruction can be required.
But the reason grazing hurts is because, like a carpet burn, it stings. Some people don't graze at all! For those who do, peeing with hands on the floor and butt in the air helps (and you also have the benfit of looking super classy while peeing), and URAL can help take the sting out of peeing too.

With stitches, I think the worst part (because it's unexpected) is that healing itch. Showers help, salt baths help, as well as the flushable toilet wipes you can get. Ice helps with swelling. I think the midwives used to cut into the stuffing of a pad from the end and fill it with ice.

I hope you feel more informed now, and not that scared. Many women tear (many women don't!) and in the great scheme of things, while inconvenient and uncomfortable, usually isn't as bad as is sounds in theory. xo