BlueFolly thanks 
Buckinbronco it is not the fault of the OP, she was snitched up. She needs empowering right now not trashing. The bride will cope just fine.
What white lie, OP? You don't need to say but I am feeling relieved if this means you will not take out he loan.
Re "I'm struggling with how I could pull out or let people down." First stand in front of mirror and say 10 times "I am not letting anyone down, I am looking after me."
Then speak to bride, explain situation, face to face, phone or email, whatever is easier for you. Say what you want to say, you felt a bit pushed into it by Friend 2 not by bride (if that is true) and now you are feeling stressed because as you said already you absolutely cannot attend and cannot pay for it.
Most importantly what do you want to do? Do you want to organise a local thing for bride? If yes, offer that.
Then tell Friend 2 and decide what will happen. Will friend 2 organise a big event which neither she nor you can go to? Good luck to her.
I'd go with DoreenLethal - Brilliant idea "So send another email out saying 'back to the drawing board ladies, a night out locally is going to be the better option. Will be in touch'."
I can almost guarantee you that some others will be relieved that the trip if off and a fun local night is on the cards.
Yes, you are right OP it isn't "... ialways easy admitting you're totally broke." I am married and my dh is very tight with money! I hated it at first until I saw others buckle and have huge financial problems., He's eased up a bit now but to be honest he has kept us a float. Learning good money skills is hard, I am 51 and would probably be bankrupt now if it were not for DH. Learn some financial skills, think of them as life savours.
BUT remember - you don't need to say you are skink you just need to say "I can't afford that." If people push just smile and say what I said to DH tonight when he accused me of eating his cream egg and didn't seem to understand when I said not me! I said something like "I find it really insulting you don't believe me!" (True story!) 
Sort this for you......
Do it and come back and tell us once it's all over! PLEASE!