Remember your worth. Remember your strength. You sound determined to never give up and I think that is most of what you need right there. I know it is difficult to throw your worries away, but you shouldn't burden yourself overly without it absolutely being necessary. If you cannot find alternate transportation and the distance is too great or dangerous to walk it then you may have to contact them and explain and possibly pull yourself from the position for the time being -- just whatever you do go easy on yourself and remember to treat yourself with the same kindness/respect/advice you would give another if they were in your situation.
I have been in some tough spots in my time and I actually enjoyed the most difficult of them (now I didn't intentionally inject myself into making things the most difficult as they could be, but when I was met with such I adapted and toughened my resilience). Once in a similar situation as yourself regarding the loss of transportation and a new job I was finding myself getting up for work two hours earlier in order to walk the 10 miles I need to travel (I could easily sustain a 5 mile an hour walk, at least for only 2 hours but I know that is a bit much for many people). Something about such troubles always put a smile on my face -- maybe it was part of the male "conquering something" type thinking -- but I always enjoyed overcoming adversity. I was careful to only allow myself to experience joy over the walk and I would never indulge in self pity or allow myself to feel angry about the situation (for instance the day it unexpectedly rained when none was called for and I had no rain gear or umbrella with me at about the halfway part of the walk).
I suspect that regardless of what happens in the immediate that you will do quite well in the long run so just go easy on yourself in the meantime and best of luck to you.