Well, well. The obvious answer to "If I had money, I would have left." is "If you had a job, you would have money and one of the things that makes me tense would evaporate. Maybe things wouldn't get so ugly that you want to leave." You don't support him? An engine only has so much steam. How do you financially support a family, including another capable adult, and also have the energy to stand around being the cheering section? I hope you are very clear in your mind that this is total nonsense. He imagines it would punish you if he left? Punishment? Yippy Skippy!
Warts and pond slime! Croaking and bug breath! You did great. The breakdown you had was related to his endangering your puppy... something you love. It's always harder to let go when you go into protective mode.
But may I suggest you tape a copy of the serenity prayer on the telephone and make yourself read it before you call his parents again?
Stop beating yourself up.
love and hugs,
Smoke