I was outed

I told one friend about my feelings towards another girl who happened to feel the same... today at lunch someone was spreading a rumor that we are together (we are not). He flipped out screaming, yelling, and confirmed my sexuality. My best friend now knows that I'm involved with another girl, and that I may be lesbian, and her family is strongly Christian. One friend has started ignoring me entirely.
My mother frequently has mood swings from what my father supposes to be a hormone imbalance. She will scream at me and throw things when she's at her worst, but be the most loving and caring mom at her best. My father is homophobic and refers to lesbians as 'dykes'. I live in a small protestant town and I'm suddenly faced with the fact that I could be outed any minute to my parents.
I'm fifteen and female and I'm scared. Two of my friends accept me and the other, who is gay, is treating the situation like it's a joke. I'm so tired and scared and I feel alone and I'm beginning to question myself. I know that I like her and that it feels right with her. I'm a smart student, 3.8 gpa, advanced classes, a lot of extra curriculars, etc. Her friends regularly smoke weed and I know that she's fighting more than one mental illness without the support of her family. I'm scared, and I don't want to be the way that I am. There is no telling how my mother will react - but I'm seeing it as by now it may be worth dating the girl I like due to the fact that nearly everyone else has left me? Should I tell my parents? I am scared that they will hear a rumor, but telling them is very scary as well. I'm doubtful if denial will be possible after what my friend yelled...
And besides that is the question of my sexuality? I'm not attracted to men at all, I hate physical contact, I amvery sex-repulsed by both genders... she is the first girl or person that I've been romantically attracted to. I think that this means that I'm homo-asexual or possibly demi, but I'm not sure? I would really love any advice of any kind... any words, please, especially within the next hour or tonight if possible. This doesn't seem possible:help: