I would say first and foremost you need to work through why you fell into this situation. The fact you say you needed love means you haven’t dealt with the impact of your first marriage. This should be a priority.
Love and attraction are intoxicating, these are strong emotions that overwhelm. Hate and anger do the same thing. As a result our good judgement and our rational thoughts get sidelined and over ridden. Then we start to make bad decisions or even worse let bad things happen.
In your post you state he is a narcissist. At the very least he is morally dubious. But you need to really come to terms with the fact that he can manipulate you and you must stay away from him. Grey rock is the way forward. Get him out of your life and out of your head. That is your win and anything you do that keeps him in your head or life is the wrong move.
There are only two things you need to do now. The first one is to divorce. End the marriage and get a consent order to protect your assets. Have minimal contact and interactions with him during this process. You have no need to show cause or blame to divorce. So don’t go down the rabbit hole of trying to convince him or anyone else he was to blame or he is a narcissist. Just get divorced.
I don’t know what is going on with the loan and why you are paying money to his ex. If you are then stop it. And no one can repay that money to you except him. Any debt that existed before the marriage is his alone.
There is nothing stopping you reporting him to the NMC. But there isn’t anything in the post that when looked at objectively is provable or actionable. You won’t be able to prove he is a narcissist. His actions where to marry you and during the course of your relationship you took out a loan and used the money to pay off one of his debts. That was something you agreed to do within the relationship. It’s shit but not necessarily fraud or deception. Married couples do this sort of thing. I would say the case will go nowhere but if it did you will need to give evidence and all of that will bring him back into your life. Without a visa he can’t work anyway.
The important thing now is to protect yourself. He can get in your head and he can manipulate you. Do not give him the opportunity. And that means distance and removing him from your life quickly and painlessly. If you take actions which threaten him he will retaliate. He might also seek to win you back and that would be disastrous for you.
Stop paying money to his ex. There is nothing stopping debt at all and it’s not yours to service.