This claim is baseless. Those who claim this false story say that Safawi ruler forced Sunni to follow Shia faith. Millions of Iranians are still Sunnis and no one forced any one to accept Shia faith. Safawis ruled over many countries including Iran, Afghanistan and parts of Indian subcontinent but history never recorded any force on any one in the matter of faith. Till today Sunnis of those areas are still Sunnis. This fact itself is a living evidence against that false claim.
When you believed in the fact that Ahlul Bayt (AS) are the real divine leaders of Islam after the Prophet Muhammad (SAWA) and followed them, you don't need to declare that in the form of Shahada. You should be already doing that in Azan أذان and Iqama إقامه.
It is good to say that again if you wish but it is not a condition for being a follower of Ahlul Bayt (AS) as far as you believe in it.
Jum'a Prayer has many conditions including that it should not be performed if another valid Jum'a Prayer is been performed in radius of 3 miles. If the Jum'a Prayer near your area is not valid according to Ahlul Bayt (AS), then you are allowed to perform a valid Jum'a Prayer with minimum of five participants including the leading person who must be having all the conditions including being 'Aadil ( pious) with perfect recitation of the Prayers.
Shura, as done during early Islamic history, is not the same thing as modern voting, a modern parliament, or modern democracy. Modern democracy developed recently in history, and some Muslims back-project it and claim it has roots in Islam by saying it is like shura. However, modern democracy is different from shura, and this is not an accurate analogy; rather, it is a form of apologetics.
In any case, the Shii belief is that the succession to the Prophet (S) was appointed by Allah and people did not have the right to choose it - neither by shura nor by a one-person-one-vote system - just as people do not have the right to choose how many times a day they say formal prayers, or what month to fast in.
However, Allah has not appointed specific individuals to be our political leaders presently, so we use other systems of governance and selection of leaders.
Furthermore, when you read the history of what actually happened during the selection of the first three caliphs, you see that some things happened that were questionable or politically motivated for an agenda, and it was not that everyone got together and simply discussed with sincerity and equality who should be the next leader. The scenario was different for each caliph. When you read what happened, you see it is nothing like voting today where every person has a single vote and the majority wins. You can look into that in history books.
Divorce is not the way in such cases but to try to explain to him the facts which you discovered about the Real Islam, so that he may realize as well. If he refuses the evidence and insists on that, you can continue with him as far as he does not obstacle or disturb your religious freedom or practice.
I advise you to keep on explaining and giving him useful information which can help him to know what he does not.
We don't have such narration suggesting the Prophet Muhammad (SAWA) is from the tribe David. David is from Ishaq (AS) while Prophet Muhammad is from Ismael (AS).
You need to ask the person who claims that to provide authentic evidence supporting his claim.
Fadak was mentioned in many authentic narration in Shia and Sunni books. The narrations about Fadak in Shia books are so many that many scholars complied whole books on this matter.
Shawaahid Al-Tanzeel by al-Hasakaani شواهد التنزيل للحسكاني is well known book containing many Hadeeths fron Sunni sources in favor of Imam Ali (AS).
We are allowed to listen to any reciter of Quran as far as he does not openly deny the main orders of Quran.
Nasibi is the open enemy of Ahlul Bayt (AS) which means the he is rejecting the Quranic verses in favor of Ahlul Bayt (AS). Nasibi is in fact an enemy of Quran even if he recites or memorise it. We should avoid supporting any Nasibi.
Shia Muslims are the real followers of the authentic teachings of the Prophet Muhammad (SAWA) and they will be going with him where ever he goes. The Prophet himself called his most pious followers as Shia of Ali as you see many Sunni books like:1. Shawaahid Al-Tanzeel by al-Hasakaani, V. 2, P. 66.
2. Al-Durr Al-Manthour by al-Siyooti, V.6, P. 379.
3. Yanabee' al-Mawaddah by al-Qandouzi Al-Hanafi, P.62.
4. Al-Manaaqib by al-Khawarizmi , P. 187.
5. Al-Sawa'iq al-Mohriqa by Ibn Hajar , P. 96.
6. Tafseer Al-Tabari, V.3, P. 146.
7. Tathkirat Al-Khawaass by Ibn Al-Jawzi, P.18.
8. Fat-h al-Qadeer by al-Shawkani, V.5, P.477.
and many other Sunni books.
What you heard is completely false. The Prophet Mohammad (sawa) is the greatest of all creation and if anyone puts someone above his status, they are out of Islam. Such a belief would also contradict the ahadith of the shia which clearly state not to put anyone above Rasullah (sawa)
May Allah swt grant you success
Islam is not a fashion show. Many Muslims today focus on things that are not important, and judge and criticize people for minor things while the world is burning.
Our big problems are dictatorship, economic inequity, racism, classism, consumerism, materialism, shirk through worshipping the ego or false ideologies, poverty, warfare, social breakdown, and environmental degradation. What color clothing people are wearing is not the big problem. It is allowed to wear black clothing or white clothing or any other color clothing, and it is wrong to prohibit the things that Allah has allowed. There are enough haraam things.
Their criticism is based on a sense of dislike of the other (a sort of tribalism - those people are different from us and do things different from us, so they must be wrong), and if they don't criticize this, they will find something else to criticize. This attitude is one of the defects that some human beings have - people often fear or dislike people who are different than themselves and who seem "foreign". It is one of the things that Islam should ideally remove from people, but sometimes there is still progress to be made.
Besides, in places like Saudi Arabia, it is normal for women to wear black outside, and women are half the population, so it is really a strange criticism.
And, many people say that green was the Prophet's (S) favorite color. This is somewhat beside the point, but just putting it out there.
Also there is no requirement in Shi'ism to wear black, it is simply a custom that has developed in many places during certain time periods. But Shi'is are religiously allowed to wear any color they want.