How do people do it?

It just hurts so much even though we made the best choice for the both of us. She chose to break up with me because she said that she has no idea what she want in life right now and that the love she has for me is more like a family member than a romantic partner.

We agreed to have a mutual break from each other but still remain as friends as we have been each other's best friend before we got into our relationship of 6 years. For context we know each other for around 10 which honestly makes it hurt even more. Even though I'm not technically losing her as we're still keeping in contact, it still hurts so much. Every time I see her, all I can think of is what could've been between us...

Just how do people deal with this pain? This crippling pain just hurts so much.