Custody help

I'm in a very toxic relationship and I'm trying to get out but I want full custody, the reason why is because I have taken care of my son the day he was born, I take care of the house I cook and clean as I am supposed to as a stay at home mom and I dont mind BUT my spouse has gotten so angry towards me and never does anything with our son he barley helps me. He probably changes his diaper once a day if that and always blames me while he and my step daughter just sit around doing nothing and he smokes pot constantly and sits outside for hours on end, he is emotionally abusive and im just done with it. I can't say anything without it being a problem to him and I want my son also because he takes off on trips all the time and doesn't look back but the other huge reason is he just had a mental breakdown and was telling me how suicidal he was and thenhe said he just wanted to disappear and never come back and I convinced him to calm down and stay then the next day he acted like none of that happened but as we were driving he had multiple bad anxiety attacks and had to be rushed to the hospital and now he is acting like everything is fine and nothing happened... i don't trust him around our son...he is a good dad when he actually pays attention to him and not his pot or phone.... i want full custody and he can see him with supervised visitation until i feel he gets the help he actually needs...is that reasonable? This whole thing just keeps breaking me qpart... i never wanted to split our family up but I cant take the abuse and I dont want my son to think that this is what love is

.... what are my chances of getting full custody? I'm in CA the only thing I can think of thats negative is I am a stay at home mom and don't have an income which I will need to get a job im praying from home.