Saving Zena from her pain

Unfortunately we have come to the realization that our lovely awesome friendly sweet dog Zena is no longer living a happy and peaceful life! She has tumors all over her body, and in the above picture u can see the worst one on her leg. It is now leaking blood all over and today she has started throwing up blood and mucous.. I am so saddened that it has come to this. But for the unwanting to put her through anymore suffering and pain, i feel it is in her best interest that we put her down.. Unfortunately i have 3 kids and dont make enough money at my job to be able to afford to put her down.. I am begging for help at this point. So me and my family will no longer have to watch her suffer! So please help me put my baby down... I thank everyone for their help in advance