I haven't been there but no one has posted yet so I thought I would give what I would think

So I guess if you get in your mind really strong the reasons you are leaving and why they won't be changing (even write it down if you think that would help in a weak spot)

Open up to others who you trust and are supportive the exact reasons why you are leaving, if others know the truth they could help be your strength if you are having trouble not returning

Have a plan for how you are going to make it happen, call centrelink (I think you can start getting payments before you leave the house if you are seperated) look at houses, have some furniture etc all organised and that way your know you have something to go to and a way of making a life for you and the kids.

And I think maybe get some counselling. I think it is so so important to get to a point where you are fine with being on your own, you know you can be happy and healthy and everything else all by your self and then when you get into a new relatuionship you will know its because you want to not because you need to

wishing you all the best