Flier,
Honesty in friendship is really important. You've kinda backed yourself into a corner and there are just a couple options of getting out. Walk away from the friendship which will hurt everyone and be final
OR
Fess up and explain just like you did here why you did it. Say your sorry and the rest is up to them. Only they can decide what is best for them.

Chances are they will forgive you after they have a little time to think about it. Things may be a little akward for awhile but you have the opportunity to earn thier trust back.

I recommend option 2. It's not final and you very well may be able to keep one if not both of your friends. Option 1 everyone loses.

You may as well get it over with. I know it's hard but it will eat at you and postponing it will not make it go away.

Take care of yourself,
Heidu

Though no one can go back and make a brand new start, anyone can start from now and make a brand new ending.
~ Carl Bard ~