Thinking of leaving my husband and I have an 8 mth old...?

I am thinking of temporally leaving my husband. He quit his job without having another one lined up and expects me to provide all of the money...well I just can't do it no matter how hard I try. We are going to be kicked out of home on the 1st and I want to just go and stay with my parents at that time with our son while he gets his act together. I live in Washington State and my only HUGE concern is my son. I don't want to lose him and I really don't trust my husband to take care of him for even half of the time (he is not responsible). He WILL fight me about this though because that is just who he is. So how do I go about this legally? Anyone have some good resources for me?? Any help will be so much appreciated!