Problem with friend. Please help!?

I have a best friend (Angela) for 7 years, but i also have 1 more friend (Jane) with who we are best friends. Well, i don't like Jane, and i think she spends too much time with Angela. I'm afraid that i'll lose Angela, because she said few months ago that Jane is as good friend to her as i am. Jane tells all her secrets to Angela, but none to me. Yesterday i was with Angela and Jane out and i felt like i don't belong there. I don't want Angela and Jane be such good friends. I'm confused. What should i do?