Ok, two things here:
1. Don't be too afraid to tell what really happened. To me that shows pride and if it happened from not listening to others advice to begin with, it will most likely happen again. Next time might be more than a little gash on the arm.
2. It is really time to slow things down here and wait until you've got the proper tools/materials to build a SAFE usable bow. I'm all for tinkering and experimenting but it's not worth a serious injury.
Heal quick and listen to the people here, they are trying to help you.
Kip