You seem clear in your head and heart: you do not want to be a jw.
You do not have to justify yourself. As others have said. Just tell them that you are no longer interested.
They will try and " softly softly" ask why, etc etc . They are trained to deal with this kind of situation.
You must be firm.
If it is not your personality, to be firm, and you are a little afraid, maybe ask someone to be with you. They could wait in the kitchen/bedroom, intervening if the person gets too pushy.
And frankly, you do not want this person to stay your friend. Its not their fault, but they are programmed to keep coming back and trying again, always on the charge, always waiting for a moment of weakness. It would be better for you, never to see them again.
Good luck. Be strong. We are thinking of you.
very practical ideas anewme