The way, you are trying it does not sound good. You can try it in the following way.
- Add your css in separate file like
- Add your script in separate file like
- Now create a text file like
Upload all the files in a assets library like Site Assets
Now open the text file and add css, js reference and also add other html.
<link href="/Site Assets/myStyle.css" rel="stylesheet" type="text/css">
<!-- Write other html code here -->
Now link this
myCEWP.txt file with your CEWP from browser.
Update: If you need this
myCEWP.txt file under SharePoint Source Control, see the first comment by DannyEngelman. I found a problem in Standard version 6 months back. May be it is not there now.