Hi Seastorm,
I am so sorry for what you are going through. It is going to hurt and hurt and hurt and one day the hurt will lessen and become bearable. Until then, lean on us and whomever else you have, and don't worry about doing it. You need it. Do not try to deny your needs right now.
Except for the need to contact your ex. I have an idea about that. Ns frequently use a kind of good cop bad cop routine where they are both. They hurt and betray you, and by the way, they are the only ones you can turn to for solace because they have cut you off from everyone, and even if you have someone else, the crazy reality you are living would be too much for anyone outside the relationship to understand. So you turn back to your abuser to 'heal' the wounds your abuser inflicted. In order to make this work, you have to deny at that time that your abuser is as bad as he really is, in order to get the comfort and respite you need to keep on living. So this habit of denial is begun.
Now you are hurting, and of course you wish to turn to your only previous source of relief, but also of pain. This is a long term habit that will take time to break. Not only our mind is involved. Your feelings and coping mechanisms are deeply entertwined with this behaviour and you will take some time to unravel it.
In the meantime, all you can do is make a goal of not doing anything to maintain the relationship. Try to make a T chart, just a piece of paper with all the good things about your N on one side, and the bad things on the other side. Whenever you think about it, write some more down. Keep it handy. Use as many pages as you need. When you feel the need to go to him, go to your chart and write down the thing you feel you need from him right then. Then also write down the bad things you may get by contacting him.
Sometimes just having a momentary distraction can help you regain your equilibrium and keep you from reaching out. Each time you do not reach out, it makes you stronger.
Try asking a friend to be your go-to when you want talk to N. Just ask her/him to listen without offering suggestions. Then just call that person first before you phone the N. And hopefully instead of calling the N.
I know you will get through this. It is not easy, so don't expect perfection. Just incremental improvement.
Plucky