How can I get out of the habit of holding on to the saddle horn?

I ride western and I used to always be able to go into the gallop confidently and having full control and not have to hold on to the saddle horn. But I had a really bad fall a couple months ago and now when I go into a gallop or even a trot I fell like I'm going to fall off so I guess the saddle horn is my source of confort. What can I do? I don't want to have to do that.