If I unknowingly cash a fictitious check, am I responsible to repay the bank?

I have a question where i was sent check from a Financier and 10 representives from the bank told me it was my money and one of ten even told me that my bank had received the funds from outside source after about 7 days of cashing check. Well i sent 4200.00 of 4800.00 out for courier charges etc.. only to find out check ended up being altered/fictitious. Now my bank is holding me liable after 10 representatives told me it was good and my money etc.. It has been turned over to a collection agency and i live in ORegon. I want to settle for 2000.00 and i have paid 300.00 already and the bank took out 600.00 from my account so i will have paid a total of 2900.00 total towards a possible 4800.00 debt i feel they should shoulder 1/2 of the responsibilty on. These representatives are paid to give accurate information now i have to pay the cost whatever it might be cause i can't prove anything. Should i let this go to court Hoping judge will see things my way? Or try to settle and get this behind me becuz if i lose in court things could get worse.