Someone will tell you that she's seeing someone someday and that she's happy and your hands will stop working. You'll have to work hard to hold onto whatever you're holding. I hope it's not glass, I hope it's not breakable. Suddenly, you'll remember everything that you ever loved about her. Everything that ever moved you to tears, made your insides feel like they were tying themselves into knots. That she way loyal, that she was open for you, that she smiled against your mouth when you kissed. That it felt easy, like God had put the two of you together deliberately, like it had been the plan all along.
But for whatever reason, you let her go and you thought that it was the right thing and for a little while, it felt like you knew exactly what you were doing. Except now, all the part of you that touched her knows that you're never going to be able to touch her again and that hurts. Even your fingers are sad, even your stomach is aching from the loss of it all.
You're never going to get that again and that's why your regret looks like artwork that would have been a masterpiece if you'd finished it. Your regret looks like plucking a flower before it's bloomed. So maybe you'll call her later and you'll tell her that you miss her and she'll sounds gentle on the phone but not in love with you anymore.
She'll say "we happened and we were important but you let me go, I'm sorry, but you let me go" and that's how you'll know.