Coming from her hurts because it is so final. When other people say it it doesn't hurt as that tiny part in you still has hope (even if you don't want reconciliation and your intellectual part knows this) so when it comes straight from the horses mouth it hurts. It may be an ego thing too, our ego hurts with any sort of rejection.
Good luck moving on. Don't beat yourself up about the text. Without it and without her response you would still be in hopeland. Accepting it is actually 100% over is the first step in the healing process. It will get easier from now.
Some people are drains and some are radiators... Keep clear of the drains and hug the radiators!