Salam Alakyum sister,
We as Muslims are supposed to enjoy what is good and forbid what is evil and it is are duty to enjoy one another to truth as Allah says in Surah Al-Asr.
and exhort one another to preach Truth, and exhort one another to be steadfast.
Having said that we are to leave the company of those who abuse and slander Allah swt, Prophet Muhammad (pbuh) and the Companions (may Allah be pleased with them).
So one has to make a quick judgement as to whether on this issue. He wasn't here to learn, his only objective was to lie and slander, no matter how much proof you will bring forth to him he will not listen. So its better to leave him because the more you argue with him the more he will lie and slander (which is quite obvious). Had we kept quiet these thread would not have gone this far.
May Allah guide us closer to the truth.
Ameen
Salam o Alakyum