How do you know it's time to end a relationship?

When did you know it was time to leave your marriage? I love my husband but things are getting really bad at times. We have 3 kids (9,5,2) I’m at a loss. I don’t wanna throw away 8 years! & miss out on my kiddos life’s by not seeing them everyday. Hes a great dad & husband but his anger and hurtful words are getting to much