I am really scared to ask this girl out what do I do?

I wouldn't wait any longer or to be honest in my opinion you may of left it to long. If you want to ask her out don't do it directly 'will you go out with me' makes things awkward for you and her and it gives it a greater chance she'll say no. The other is the best way to ask a girl out is face to face but obviously you can't do that.

So heres what i would do assuming she lives near you doesn't really matter though text her and say or even drop it in next time you are texting her and just say ''i am going town later too have a look in some shops. Meet me up there if you can'' or '' theres this coffee shop that do the most amazing monca coffee on this planet. I am going up later to try one out why don't you come along''. Also shows that you are doing what you want and not going out of your way just for her which makes you less needy.

Hope this helps

P.s Also never ask her to the cinema or anything because you want to get to know her and not the film plus when you go the cinema ereryone always assumes they will kiss and etc which you will be not at that stage yet. The other thing i would suggest is forget about your old relationship. Thats in the past you need to move on. If this girl says anything than ok or diverts her answer to a no then don't be disheartened be proud of yourself because you had the guts to ask her in the first place. :)