Get on the phone and start calling the vets in your area. Explain your financial situation to them. (Be honest). If they are unable to provide the service themselves they will refer you to another vet that will. Good luck and do the right thing.
god I hope you took kend,s advise , the most humaine way is the shot, most vets cost about 90 and they take care of remains and most will do payment arrangements, but stay with it till its over, its very hard but give you clossouir