No one should ever make you feel ugly or unwanted. Every one is beautiful in her own way. Every one needs to be loved. Your boyfriend's choice to masturbate in front of you, instead of being sexually intimate with you, is insulting.
You need to ask yourself why are you staying in this relationship. Move on, you deserve better. Continuing in this relationship can negatively affect your self-esteem. The longer you subject yourself to his sexual avoidance of you, the worse you will feel about yourself.