This issue happens more frequent than not. I just read one last night in another platform where a crafter claimed to have had his "holster" design copied (stolen) yet I know another crafter who has been making them for almost 8 years when I first me him. Whose design is whose original design. I think we see something, consider some changes and tweak it to fit our artist needs. I agree that you should not depend on one product. Constantly challenge yourself to better your design and move forward. I am not in business with my leather items, but if I were one priority for me would be to stay ahead of curve especially with social media. You can almost bet that your design will be copied within a few days of posting pictures, so be ready.
Take a deep breath and move forward to your next best idea!