This is a great visualization of what the person being broken up with may feel like. I certainly know I have been there before. I think a helpful tip in such scenarios is to have enough of “you” to love and to be defined. This will help with not making their existence in your life the pinnacle of yours.
But no matter what, if someone breaks up with you and you love them it will hurt no matter what.
In addition if you can, remember they are breaking up with you b/c of something within them. Try and think: there are 300m people in the US. If we remove the too old, the crazies, the weirdoes, the same sex, and all others that you would never be “happy” with; you are still mathematically compatible with at least 1% (300k) of people you can have a wonderful relationship with!