I know you want to go back to him because he knows you, he understands you the most, she knows everything about you.
So why did you leave in the first place? What made you leave the number one go to person in the world?
If you were crazy and at the same time, sane enough to leave, then keep it that way.
It may not have been toxic and that’s your excuse. However, that it’s familiar doesn’t mean it’s right. That it’s right doesn’t mean you need it at this phase of your life.