Don't want anyone to feel left out... so please help!

Hi you all! I have a real problem but haven't got much time, as I'm going to meet my best friend right now, but I still have got something on my heart so I want to tell it now.
(Forgive me for my bad english!)
So. There's this best friend of mine.. there's a friend of mine and hers who's going with us to the same gymnasium and with who I have been in class for 2 yrs.
We liked each other but didn't know how to get along, so the ex-classmate of mine and I were having a good 'classmate relationship'. now lately i had even fights with her, but now everything's fine and she's really trying to make me see she likes me and that always gives me a warm feeling.
that's not the problem.
tomorrow, there's going to be a huge party in my gymnasium. i so want to go, but on the other side i really think it won't be such a great party. so if i wouldn't go,
my best friend and i already thought of watching DVDs together.
now this other classmate of mine, heard about it and was like: 'oh ive never seen this movie! (pride and prejudice)' and i was like: 'you want to join us, so?'
i absolutely have no problem her joining us.
but i think my best friend has got a little jealous since she saw that this other friend (it's my best friend's classmate) and i get much better along and are developing some kind of fundament for a friendship.
now what shall i do? i don't want her to be disappointed. help!
she's coming!

Just assure her that she's not going anywhere, that she'll be your best friend in this whole friendship. sure, that could change gears, but for now, she needs to know that youre there for her.

and i think its great that youre making new friends, just dont forget to remember your old ones!

Thanks a lot, especially for the encouraging!
that made me conjure up again that i really have the right to get along better with this other girl. i mean, she's not flawless either, but a great, religious girl with a good heart.
i'm going to do exactly the same thing when i think my best friend is getting the wrong ideas.

so again: thanks so much!