First of all just breathe...in and out...deep breaths...have you calmed down a bit now?
Its alot harder to try and figure things out if your completely stressed about them so you need to just relax a bit
Anyway, Steph has already asked you out then or...? Sorry i dont really understand what you mean about next friday and steph asking you out already or...umm...yeah...could you explain that again thanks
As for the part which i did understand
lol ...i agree with soontobehomeschooled, i think you need to be honest with Steph about your feelings towards her, if she has managed to build up the courage to be honest about her feelings towards you and ask you out, then i think its only fair that you return the favour, right?
And i suggest, if possible, that you do this before you ask Carly out. You may even want to discuss Carly with Steph? Im not sure what type of relationship you have with Steph, if you would talk about things like that, but that is entirely your decision...Just make sure you are honest with Steph about your feelings for her.
I know you said that you dont want to damage your friendship you have with Steph, but if that friendship is worth anything then surely she will appreciate if you are honest with her. She may not feel that way immediately as rejection isnt the easiest thing to deal with, but she should realise that its better than you leading her on just so you dont hurt her right now, because i guarantee it would hurt her alot more if she found out in a few months time that you dont feel the same way that she feels about you...dont forget to let her know how much she means to you as a friend etc
Finally, with Carly, i think you should go for it. You missed your chance to ask her to the dance so learn from that and go for it. Like i said to you before, either way you are gaining something from this. If she says yes, you get to be with her if she says no, then at least you managed to build up the courage to ask her, something you wouldnt have done if it wasnt for her, right? ...just think of it as some practice for next time
At the end of the day though, it is your decision what you choose to do. If i were you i would be honest and try to make sure i take my opportunities...it isnt often we get second chances...
Goodluck with things!