@VioletLemon has recognised and owned that she made a poor choice of partners - but I'm sure she didn't do this deliberately, and she ended the relationships. Like most of us, she is far from perfect, but has tried to do her best, and is now working on her psychological difficulties.
However, you are right that her children will not find what they suffered in the past easy to get over, if they ever do. Sometimes the best we can hope for is to come to terms with things - we don't know how long this will take, or how long it has already been.
They strike against their mum because she is the one who is there to hit out at; because as small children (and mentally in some ways they will be stuck in that place) they needed her to protect them, and she failed - at least to a degree; and because she has always been there to love them, and even now they are likely to be testing her devotion. Children - whatever their age - kick out at the people that they can trust to continue to love them no matter what. Her ex's are not important to them because they were a waste of space and also because there is no emotional connection. The children couldn't hurt these men by withdrawing their love, because these men don't care and never did.
That's not to say OP should get rid of her new-found boundaries - on the contrary these are very important both for her and her children - but she will find that they kick against them, and it will take time. They may leave her, for a short time, or a long one, but for all of their sakes she needs to show that she is there for them, but that there are lines they must not cross (eg drugs, loud music, strangers in the house etc).
As they grow and mature (and they need her to have boundaries in order to do this) they will come to realise that they are safe, and that she is there for them, but that they need to behave appropriately. It is important for everyone's sake that she maintains her stance.
Edited to acknowledge the wisdom of @StopStartStop 's post, above