When my cousin came out I said, "No duh. If you always having your "friend" with you wasn't a hint the rainbow triangle sticker on your car was."
@Crooooooow, if your family is fairly accepting of gay people in general then that is a hopeful sign that they will be accepting, but if they have no clue do expect them to react with shock, at a minimum, and maybe even in a way that you will perceive as negative purely because it changes the perception they had of who you are. To some parents who believe they know their kids it's about like having their kid walk up and show them a third arm. It's a shock because they didn't know, might be mad at themselves for not knowing and reflect that at you, and just need a chance to process this new information. If their reaction is less than ideal just explain that you just accepted this about yourself and you will give them some time to process it and then go find something else to do.
Also, the way you describe it with the anime and such, it sounds as if you were converted. That might be how it felt to you, but chances are that as your adolescent changes came on you became more aware of an attraction to "cute" male characters in anime and began to notice similar traits in real men. Describing it that way could allow people to think you are one trip to camp away from being made straight again.