@Anandi most narcissists develop from some kind of "abandonment" in their history/childhood so when it comes to ending a relationship with them it's important to do your best at remembering their going to "react" IF they feel they are being abandoned. Anandi, it's not a situation where there is some kind of property or children etc., involved so the safest route to take is to make the break in a way that allows him to be the one who is leaving and you to remain kind and respectful as he will need to disconnect feeling HE is the one that has more and it's best for him to continue to grow and gain as he has outgrown you. Give him that even though it's not really how you feel. He will never get how you feel, it's always going to be what he feels or needs that he cares about the most.

Privately you can thank your lucky stars that you don't have property (or private information you have shared with him) or anything with him yet that he can use against you in some way. It's always important to remember that when it comes to narcissists or toxic people it's THEIR EGO that matters to them the most. And THAT is exactly what this man made clear to you Anandi.