My partner is mean to the kids

I just can’t do it anymore. We’ve been together 8 years. He’s always been short tempered and at times emotionally/ mentally abusive to me, but sometimes he’s an amazing person and father.

Recently, I don’t know where that amazing person is. He’s in a bad mood all the time. We have two kids (son is not mine) and he barely spends time with them. He’s pretty good with our youngest daughter (2 yo) but his son (8 yo) and I get the brunt of it all. He gets home from work and gets straight on his phone, he doesn’t help clean (even though I work full time from home and still help out). He wants things his way at all times and is straight up mean. He told his son to shut the fuck up the other day and that “unless I speak to you, you don’t get to speak to me” after his son had argued with him. It’s abusive. I’ve stayed so long trying to fix the family and hoping it would help. His son asks me all the time why his dad is so mad (the mom is half in half out) so I feel awful leaving his son behind.

I just can’t deal with the toxicity any longer. My daughter has started to pick up on it and when dad is mad, she follows him and tells me she doesn’t like me. It’s breaking my heart. I don’t know what happened. Or if I’ve just been so blind. (We’ve tried family counseling but he says he doesn’t have time)

Do I just get the strength to leave or what do I do?