Vickstar

This is not the first time this has happened.
A bit of back story.
1. Husband has three girls (16, 14, 8) with crazy drug addicted ex that cheated on him repeatedly and they used to fight violently.
2. 14 & 8 now live with us (and have for the last couple of years)
3. We have a beautiful just turned five year old boy.
4. My husband goes away for work for weeks at a time leaving me to care for all three children alone.
5. I work fulltime, study part-time, and am involved with the school.
6. He went on a seven day no contact hunting holiday just recently that we could not afford, while his mother was staying with us, and left me to deal with everything, including her.
7. Him assaulting me has been happening on and off for a number of years, but recently it is getting worse, physical bruises, being unable to walk etc.

I know I have to leave him. I really wanted to make it work and keep trying but everything is my fault. He decided that it was more important on our sons fifth birthday to go and check on his cannabis plants in the bush with his mate than to be here to put his son to bed on his fifth birthday, the day before he started school, and then he went away for the week, has not seen much of his son this week, and has not been there at all to support me who has been really struggling with it.

Then when he got home he starts grumping about the kitten that I rescued, and his daughter is saying "why do we have to keep the cat anyway". This began an argument. Which then turned violent.

I never physically hurt him, though throw some emotional punches sometimes. I throw at him that his behaviour seems that he doesn't care about his family - but you know what - it does seem that way.

I'm scared to leave because I really dont want to hurt my son, but I know that I/we can't live like this anymore.

Not to mention that the step-daughters, as expected, are on their fathers side, ignore me when he is home, particularly when asked to do something, and then everyone gangs up on me.

Help...