Padme did not actually "know" that Anakin was still alive. She merely felt that he was.
If you are asking about Vader post-Mustafar, then no, she doesn't. Padmé doesn't seem to know Obi-wan cut off his limbs and left him to burn alive, Obi-wan didn't believe Anakin to be alive and Anakin's surgeries were still happening as Padmé died so there was no way for her to know.
Mike Chen's new Star Wars novel Brotherhood reveals Obi-Wan Kenobi knew about Anakin and Padmé all along - and chose to keep their secret. Star Wars has confirmed Obi-Wan Kenobi knew about Anakin Skywalker's marriage to Padmé Amidala all along.
Had Anakin not converted: Padme would have been killed by the Emperor before childbirth, and before Anakin and Obi wan returned from the mission to destroy general Grievous. Regardless: order 66 probably still would have happened since the army was under control of the dicator in Palpatine.
Anakin does not have even the slightest bit of remorse. By the end, he feels nothing but anger. Although he feels regret for killing Padme, he still helps the evil Emperor. The film ends with Anakins standing side by side with the man on whose behalf he has committed all his crimes.
After Padme died, Anakin had already fully committed to the dark side. Even if he still desired to do good, his anger had corrupted him to the point of no return.
What Padmé knew about Anakin's previous dark deeds. Padmé was well aware that Anakin had committed dark crimes that would've started his fall to the dark side. He even confessed to her that he had massacred an entire Tusken Raider village to avenge his mother, leaving no one alive.
Padme's death is the moment that solidifies Darth Vader's fall to the Dark Side, and expanded Star Wars media has often shown him mourning her when not serving The Empire.
Did Padme ever cheat on Anakin? No. As explained above, Padme did not cheat on Anakin with either Obi-Wan Kenobi or Rush Clovis.
Once inside the spiritual realm, Vader went through various trials, but eventually, he found Padmé. All indication was that Vader could have brought her back to life just like Momin did with his body. But Padmé refused to come. She threw herself from a balcony, claiming that she no longer recognized her love.
This time jump makes Padmé a very mature 24 years old, while Anakin is still a Jedi Padawan and teenager at the age of 19. This formidable time in their lives is when the romance between the two sparks, so the age difference between Padmé and Anakin doesn't hold them back.
So while it was never been outright said, it wouldn't be surprising if Yoda knew about Anakin and Padme's romance. Even with the birth of Anakin's children in Revenge of the Sith, Yoda didn't seem all that surprised.
He was still completely unaware of the Sidious/ Palpatine connection until ROTS. He also said during TCW season 6 that the Jedi order must believe in the clones and end the war before the Sith's plans are realized.
He has! Darth Vader's love and his grief was stronger than the pull of the Dark side. He visited Padme Amidala's mausoleum on her home planet of Naboo.
Arguably, most Star Wars plot points revolve around characters simply not knowing something, very often about their family history. But, on top of all of that, the biggest reason Obi-Wan doesn't know Anakin is alive is that the last time he saw Anakin Skywalker in Revenge of the Sith, Ben literally left him for dead.
However, when they next met in Star Wars: Episode II – Attack of the Clones, Anakin and Padmé's feelings for one another grew into something resembling love, and their wedding at the end of the film solidified their relationship as one of the most important romances in Star Wars history.
Originally Answered: Did obi wan and padme have an affair? No, they did not. In the original writing for the prequels, there was talk of making Padme a romantic interest for Obi Wan, so that his conflicts with Anakin would not only be about his interpretation of the Jedi way, but there would be a subtext of jealousy.
But no Star Wars movie or TV show has placed quite as much emphasis on Obi-Wan's admiration for Padmé as Kenobi has. Obi-Wan has been able to use his relationship with Leia look back on the time he spent with Padmé, and the series has made it clear that he held quite a lot of affection for her.
This is the most well-known of the Jedi rules. Love leads to attachment and attachment leads to strong emotions, which are the path to the Dark Side of the Force. Because of this, Jedi are forbidden to fall in love. This, of course, doesn't stop Anakin Skywalker from falling in love with Padmé.
Before he could enter, however, Vader was stopped by Sabé, Eirtaé, Rabé, Saché, and Dormé, former handmaidens of Amidala, who refused to let him enter into the grave so he would not desecrate it. However, Vader would not be denied. As he entered the tomb, he became flooded with memories of Amidala.
After all, keeping Anakin as Darth Vader relied on him believing he killed Padme, so the Emperor needed to make sure no part of the funeral suggested otherwise.
During the iconic opening moments of Star Wars: A New Hope, Darth Vader has a tense confrontation with Princess Leia, an adversary who, unknown to him, is actually his daughter. Despite participating in Leia's interrogation, the Sith Lord doesn't uncover his familial connection with the rebellious royal.
“Someday I'm going to fly away from this place.” Again, young Anakin's quote illustrates his aspirations. His words also foreshadow his role in the climax of The Phantom Menace.
Qui-Gon Jinn is seen by many as the best of the Star Wars prequel era's Jedi, and there is evidence that he could have even stopped Anakin Skywalker from falling to the dark side of the Force.
Sabé is the most important of Queen Amidala's royal retinue of handmaidens. During crisis situations, Sabé and Amidala switch roles. Sabé becomes a decoy, disguised as the Queen, while Amidala adopts a simple gown of a handmaiden, and goes by her less formal name of Padmé Naberrie.