@ysmina-- You need to use a lip balm with SPF in the summer. I use a lip balm with sun protection year around. It's true that sunlight causes freckles or makes them darker. But you can avoid it by using the right products.
There is nothing harmful about a freckle though. I personally think that freckles are cute and I know that there are many people out there who feel the same. A freckle on the lip is even more unique.
I don't think you have any reason to worry and I agree that you need to accept and love yourself the way you are. As long as the freckle doesn't grow or change into an odd color, it should not be removed. Like the article said, the scar of surgery will be much worse than the appearance of a freckle.