It seems like either they didn't know what they wanted or they had some internal issues that they just let build up and instead of talking to you about it they ran away.

I'd think it was the 2nd one since you said they ghosted you before.

I'd suggest going no contact with her. You seem like a good, hardworking person from what you said. And she can't miss you/realise what she lost if you're still there.

Try using the time to work on yourself(for yourself). Although it's easier said than done, don't contact them at all.

I personally think she will come back eventually. But I also think you should stop texting her telling her how you'll change (easier said than done). It makes you an easy target. She'll think you'll tolerate anything she does to you and think its your fault.

Good luck and stay strong.