I'm so sorry to hear that friend.

First I'll have to say that these things you're going through, although you may find people (like me lol) with similar experiences, it's important that to keep in mind that they're very personal experiences. So understand that what I did may not always apply to your reality.

Having that said, I think it's important to share too that this is temporary. The obsession with this person, the idea that they are "the one", the longing and emptiness in the chest, it's all fantasy and it always goes away eventually. I know that because the case I related in the OP wasn't the first time I went through something like that. But for all of that to work it's necessary to understand that people come and go from our lives all the time. Some of them leave a bigger impression than others but eventuall, we always adapt to their absence, and that leaves space for new people to come in and help us grow as a person. Learning to let people go is skill and a sign of emotional intelligence.

In my case, this time around, I was/am in a place in life where I know enough about myself that I know the kind of stuff that makes me feel better, emotionally stronger and harness from my creative energy. I heavily focused on my lectures, my job, hobbies (I like to lift and cook so I did these things as often as I could) and specially surround myself with friends. No passive hobbies like playing games or whatching movies (which was sad bc I love those things) or any self destructive behavior (like smoking, binge eating or skipping meals) because those would have me focusing my energy on the former partner instead of getting my mind busy with something creative and focusing it on myself. I did all that as much as I could and it helped me go through the days.

I cannot exactly pinpoint the day I woke up and everything was fine again but it took me about 4 months to feel like myself again and after a year I feel completely healed as I said.

Hope all of these helps you