considering losing my last FP made my mental die and my life to collapse for an entire year, this is not looking good!!

My current FP (just a friend) is a great, wonderful person but I am unnaturally reliant and almost obsessed with knowing how they're doing, what's going on with them, and wanting to talk to them and have their attention and affection every second(yes I know this is all unrealistic, i can deal with that). Problem is, those feelings have not been accepted or reciprocated in the slightest(you know, a normal amount of interaction and attention, not every second of every day) for months now; they started dealing with life and a bunch of stuff, and that's completely fine, but my stupid brain has caused this disconnection to give me constant aching anxiety and depression for every waking moment. It feels like literal torture how little I matter to them compared to how much they mean to me, and I do not see this improving ever. They are doing completely fine and even seem happier with me becoming a more distant part of their life. Yet I still fawn over them, no matter how hard I try to push myself away. I wish I could be a good person and be completely happy and content that they are doing well, regardless of me being in the picture, but I just can't.

Any advice on how to just be like.. normal friends, or even go our separate ways, without going into an extreme year-long depression and loneliness again? I have no clue what to do. I just want to stop hurting every day.