Gosh, how bl00dy awkward for you. Have you got a preference if it came down to waiting to use the twin who is currently cycling or using the twin that has not cycled before? Personally I wouldn't be too concerned about using the one who has never cycled before. It's pretty unlikely that there will be egg issues, and she should know all about the process from talking to her sister about it. But if you think that perhaps the twin who is currently cycling might be a better match it might well be worth waiting to see if she will be re-advertised as a donor after this cycle is done?
Have you spoken to ex-DH about the money again? Any movement on that front? I have everything crossed here for you hon and I'm hoping he will come to the party and give you enough to get your next cycle done