Don't worry.. Its easy for you to sort this out. I have a female diamond dove that had the same problem. I took her to the vet the first time and it cost me a lot of money, and the vet stressed the poor bird out badly. even making her beak bleed.
So I decided to do it myself next time.. it was very easy!!!
Just wrap the dove in a light weight cloth to keep it still and stop it injuring itself. Not too tight! Keep the cloth over her eyes too.. than they stay really calm. Just let the beak stick out.
You can put the 'wrapped up' dove on the table of get someone to hold it.
Use a small nail file to gently file down the beak to the correct shape.
Its important to keep filing in ONE direction.... out from the birds head. Don't go back and forth like when you do you own nails.. otherwise the beak can start to splinter. Put a finger on the opposite side of the beak as you do it.. to hold it still.
Don't take too long. You don't have to do it all in one time. After a couple of minutes put the doves back in the cage to recover. You can do the same again the next day if you need to.
The doves beak is very soft so its easy to file down quickly.
Look at another dove, or a photo on the internet so you can see how the beak should look.
Don't do it too much otherwise it will hurt the dove and it will bleed.
When they get this cross beak thing its due to genetic problems, or an old injury. It will keep coming back.. But usually very slowly. So just keep an eye on it and file it down before it gets too long.
Hope she will be better soon!!!