Is my marriage valid since I was an atheist when I married?

Question regarding the validity of my Nikah due to my beliefs at the time of marriage Assalamu alaikum, I would like to ask about the Islamic ruling regarding my Nikah and whether it was valid according to Sharia. I married my Muslim husband in a Nikah ceremony on 17 January 2024. At the time of the Nikah, I was not Muslim. I had been baptized and confirmed as a Christian when I was younger, but I never personally believed in Christianity or practiced the faith. I officially left the church in 2018. Since around 2015, I considered myself an atheist and identified with modern (atheistic) Satanism, meaning I did not believe in any deity, including Allah. This was a philosophical identity rather than a belief in a literal Satan. My husband knew about my actual beliefs at that time, but when arranging the Nikah, he told the Imam that I was Christian. The Imam was not aware that I was an atheist and that I had left Christianity. Approximately eight months after our Nikah, I sincerely converted to Islam out of conviction. My questions are: 1. Was our Nikah valid according to Islamic law, considering that I was an atheist at the time and not actually Christian, Jewish, or Muslim? 2. Does the fact that my husband presented me as Christian to the Imam, while knowing my actual beliefs, affect the validity of the Nikah? 3. Since I later accepted Islam sincerely, does my conversion have any effect on the status of the previous Nikah? 4. If the Nikah was not valid, what is the correct Islamic procedure regarding our marriage and separation? I would be grateful for an answer according to Islamic jurisprudence, including the relevant madhhab or scholarly opinion if there are differences of opinion. Jazakum Allahu khayran.