And it's here where I hit a wall. I know the truth that you can still love someone even after it fails, but I don't know the steps after that. How to get over someone. Or, how to get over the feelings of attraction to go back to being friends.
I can help with that. First, give yourself some time away from them. Rejection hurts, and that needs to heal before anything else; I learned that one the hard way. Second, just do what you'd normally do, but try to avoid anything that might seem romantic. Eventually, avoiding romance when around them will just be second nature.
Just make sure they don't die suddenly, because then you'll feel like you've just been lying to yourself for years and collapse into a pile of regret and sadness. But with any luck, you won't have to deal with that.
On a tangentially related note, I sit at home and feel lonely, so I go out and do stuff with church folks, and then all I can think about is depressing shit, so I have to awkwardly pretend that I'm having a good time when it's so obvious that I'm not and I come home drained and depressed and still lonely then just do it all over again a day or two later so I can pretend I have some semblance of a social life when I'm really just worrying a few people sick and annoying the rest. Yaaay.