I haven't been through exactly this, but I know a few mums who have, and honestly there is no one right answer, some stayed and worked through it, some didn't, and both paths had their own hard parts. With three young kids it makes the decision feel so much heavier, because you're weighing your own healing against stability for them, and both things are real and valid. It might help to talk to a counsellor first, even just one session, before you decide anything, so you have a clearer head going in. Family Service Centres here offer affordable counselling and they are used to situations like this, so that could be a good first step lah.