What a horrible situation - I have always hated it when my financial necessities fight against my ethics; why does taking the high moral ground always prove expensive?
So your choices are (with my own personal, inherent bias):
1) refuse to give back the deposit and carry on. (and avoid looking into mirrors)
2) see if you can get your deposit back on your new bike and start over. (if you could it would solve the problem)
3) get some kind of short term bridging loan and hope your bike sells. (risky).
My conscience would push me one way and my bank balance another.
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on a totally random, unconnected note. You spelt dilemma as dilemna - what's weird about that is I used to do so, too but that spelling has never been taught anywhere and has never been an alternative spelling yet crops up frequently in English and nobody is sure why.
https://www.quickanddirtytips.com/ed...mma-or-dilemna