You have every right to be frusterated and want to quit. It is hard work for those of us who do rescue to clean up after all of the irresponsible idiots of the world. Its very easy to get burnt out because there is so much work to be done. The best thing I can tell you is to pace yourself and take breaks when you need them. I've had to take fostering breaks and shelter breaks before when I got too emotionally overwhelmed and stressed. Having a bottle baby and getting no sleep really does make everything seem worse too. Please take some time and take care of yourself so that you can continue to help the kitties who need you. You do SO MUCH, you are a true saint.