How do i tell my parents?

Die-hard catholic... oooo!! Depends what you mean by that. If it is anything like my family, which it sounds like it is, it would probably lead to A LOT less trouble if you just keep them in the dark. I guess it depends on how close you are to them AND if you think they are actually going to accept you for who you are, you know? Honestly, if they really, really are against it, they could just "dis-own" you. Not trying to be an sarcastic, just my opinion of what could happen from the info you gave.