There is a lot more to the dynamic than the question itself provides, but I’ll answer it the best I can and in the end, it’s just my opinion and you will need to make the choice for yourself.
First, if it was an abusive relationship and you have found your way out already, I wouldn’t return. Remember what it took to get yourself to the point to leave in the first place? Remember how hard that day was and how many times you probably tried to leave before that?
And second, you have identified him as a narcissist, so I would write down those reasons you believe he is and ask yourself if you could ever have a healthy relationship.
Narcissists are unable to provide you with a healthy relationship, and when they feel like they are losing someone who offered them a lot of supply, they will do anything to pull you back in. They know how to pull at your heartstrings.
Sometimes I hear parents say, but I think it’s healthy for kids to have both parents in the home. True, but only if both parents are healthy. If someone is toxic, that is going to affect the entire household.
You and your children deserve to live your best lives, and I think you are starting to realize that since you are asking this question.
This type of abuse can have us so confused and not trusting our instincts.
And no matter how you try to hide your hurt, confusion, or upset, your children know. And they are learning a lot about how to be in a relationship with what they see from you and your ex.
Returning to abuse or a toxic home because someone is begging or being nice for a short time, is teaching them a pattern. The cycle of abuse. There is a good chance they will become the victim or the abuser in their relationships unless they have something better to compare that to. Which you have the power to give them.
Teach them to make better choices by example and to not put up with toxic or abusive behaviors, show them what it looks like when you heal and become the best version of yourself. They need to see that is possible.
They need to be in a healthy home, with an emotionally healthy mother showing them how to live their best life.
They need to see that so they can compare it to what they will see from their father otherwise all they will know is the victim/abuser relationship and we often repeat patterns in their relationships.
Make your healing a priority and just spend time with you and your babies right now.
Create a support system if you don’t already have one. Family and friends that are positive and that you and the children can spend time with.
I would say therapy for you and the children is necessary but be sure they understand the effects of narcissistic abuse so they can properly help you. Some therapists have had little training in cluster b personalities or the effects of abuse on victims so it can be difficult for them to help you move forward in your healing.
Another great tool is coaches or healers that work with victims of narc abuse. They are usually survivors themselves and understand the trauma very well so they can help you with a lot of the things you are dealing with.