If your fear is because of the pain - then your fears are totally unfounded. It's not like a normal injection pain, and it really, really doesn't hurt. Honestly.
If your fear is the physical act of pushing a needle into your skin, then i'm am sure it will pass for you as soon as you have done it the first time.
Is your DH available to do it?? Then you don't have to look, and he can do it in your bum.
The first shot is a bit scary, but once you do it, you realise how easy and painless the process is.
You will be fine - Good luck