I have a daughter with a facial birthmark and I am trying my best as a mother to implement on her in a younger age to embrace it gracefully. I think and would also like her to think that she is different and it is visually obvious; and she is not like what we see in the mass media everyday so this birthmark gives her a unique opportunity to develop a different outlook in life, accepting and understanding people’s differences; a more matured outlook then mine while growing up I should say. It is an alternative view and I think it is interesting.
So interpreting this in to your situation, you can look at yourself think positively, forget all the negative thoughts and hide them with beautiful and positive ones. Even it is just 1-hr a day in the beginning, start to force yourself to think differently and have more positive attitude. You are a beautiful lady; it is obvious in the picture. What you need is to bring back your self-esteem and be confident. It might be easier to say but people like to stare anything that is different. Not always with negative thoughts, it can be just out of a curiosity, or maybe they know other people with birthmarks or they just think it is interesting to look at.
I remember reading somewhere that a person with a red facial birthmark was saying that some people are born with white, black, brown or yellow skin and mine is red & white. So if you accept it as your skin color rather then it is a patch on your white skin, it would be another angle to look at yourself.
You already look beautiful; just add a touch of happiness and positive thoughts with a big smile on your face when you go out then you will shine! All the best : )