argh... I see your dilemma!

I'm sorry that she's hurting you, although I'm sure you can see that she's just in shock and can't take the higher road. She's not going to kick you out or let your stepdad do it. If nothing else is working, just say "ok, I changed my mind - I'm not gay" until she's ready to deal with it. Do I really think you should deny it? No - you should be proud of who you are, and I have to say that I'm proud of YOU for being true to yourself. BUT, it'll get her off your back until she's calmed down.

Just an idea... I hope you can get in to the family therapist this evening.