I came across this hadith about the angel sarsaeel of which I've never heard of before. Please help me analyz how true this hadith is. The Prophet Muhammad[saww], was in Umm Salama's house when an angel, who had twenty heads, descended upon him. Each one of the angel’s heads had one thousand tongues, and he was praising Allah with each tongue in a different language. His wings were larger than all of the seven heavens and the seven earths.
The Prophet thought that he was Jibraeel.as, so the Prophet[saww],said to him, “I have never seen you in this form.”
The angel said, “I am not Jibraeel[as] I am Sarsaeel. Allah sent me to you to marry the light to the light.”
Then the Prophet asked him, “Who do you mean?”
The angel said, “Your daughter, Fatimah zahra[sa], to Ali bin Abi Talib[as],.”
So the Prophet Muhammad[saww] married Fatema[sa] to Ali[as] with Jibraeel[as][ Mikaeel[as], Israfil[as] and Sarsaeel[as] witnesses. Then the Prophet Muhammad[saww]looked and saw the following written between the shoulders of Sarsaeel:
LA ILAHA ILLALLAH. MUHAMMAD IS THE MESSENGER OF ALLAH AND IS THE PROPHET WHO BRINGS MERCY ON PEOPLE. ALI IS THE DECISIVE PROOF THAT ALLAH USES ON HIS CREATURES.
Then the Prophet[saww], asked Sarsaeel, “How long have you had this written between your shoulders?”
Sarsaeel replied, “Twelve thousand years before Allah created Adam.as,
Ref-. Bihar V43 P123 H31.

And if it is true how can learn more about the angel. Any recommemded sites or books?

This is the only story about Sarsaeel, and it has no validity.
It says that the Prophet (peace and blessings of Allaah be upon him and his family) was in a house of Umm Salamah when Sarsaeel came to him, while Prophet married Umm Salamah in the fourth year after the emigration, while the marriage of Imam Ali and Fatima (Peace on them) was in the second year.
At that time Umm Salama was still with Abu Salama, who was martyred in the fourth year.