https://www.mangago.zone/home/mangatopic/20415736/
There's a spoiler in the comments for what happens in the future.                                            
                                                The first timeline is awful! It made me sick to my stomach.
Basically in the first timeline:
Aerok: rich aristocrat meets Kloff, falls for him. But Kloff, thinking he needs to move his obsession with Aerok to someone else before it gets bad, ends up getting himself an omega husband. He genuinely does love his husband and his husband ends up pregnant.
Aerok gets jealous and hires men to "punish" the omega. They went overboard, raped and tortured the omega to death. We later found out that Aerok hired them to simply push him and make him lose the baby.
Kloff finds out who hired those men and sets off on his way to revenge. He becomes filthy rich and takes everything from Aerok. Aerok is really bad at managing his money. So Kloff tells him he can live there but he will have to take some unknown pills. Turns out these pills torture Aerok and force him to become an omega. It's very sad how much it hurts him.
So now that Aerok is an omega, he repeatedly gets raped by Kloff even though Aeroke loves Kloff. I think Aerok flees after he gives birth to Rapiel (who's name is Kloff's dead omega husband. Mind you, when Aerok got pregnant he ends thought at first he has a chance to live happily but with Kloff, but no. Kloff takes the child and never let's Aerok see his son. 
So instead of going after Aerok. Kloff hires men to rape and empregnate Aerok for two years over and over. Aerok forced himself to miscarry every time.
So Aerok at some point is washing himself. In the river after being raped, and sees Kloff. Kloff gives him one silver coin and happily leaves seeing Aerok suffering.
Aerok sees hope and struggles to buy himself clothes, do he manages to find dirty hand me downs with his money. He goes to his old mansion where Kloff lives. Kloff is very cold to him and even slaps him. Aerok leaves feeling so sad because he loves him and is very sorry. After he sees no hope and jumps in a river with meant to kill himself. He gets rescued and Aerok's butler brings him in to Kloff who refuses to let Aerok die.
Kloff makes him live the rest of his days in a small cottage next to the mansion where he repeatedly rapes, beats, and empregnates him... Taking his children at birth, never letting him even know their names. (at some point Aerok happens to fun into Rapiel and when Kloff sees it, he takes Rapiel to the mansion, and comes back to beat Aerok up so bad..) Neglecting him when he's pregnant and abandoning him for months on end in between. Aerok still loves Kloff and tries hard to please Kloff by cooking for him or whatever, only to be beaten up for attempting to do something nice. He tries to make Aerok cry but aerok is suffering and literally can't cry. 
At the 5th pregnancy, it's too much on Aerok's body. He's so weak and sick that he starts deteriorating. He gives birth to twins. Kloff is crying because he doesn't want him to die (dumbass is in love with Aerok after all this time but refuses to still deny it), saying he's a demon. So Aerok finally sheds tears and ask Kloff to say he loves him... Even if it's a lie. Aerok dies without ever hearing it. Kloff goes crazy and lives a "miserable" life still hating Aerok for dying and abandoning him, yet he weeps for him.                                            
                                                Second timeline has the same overall events. But this time Aerok remembers everything he went through and tries to stay away from Kloff, thinking he doesn't deserve him. He's scared of him too.
Kloff doesn't remember but is plagued by nightmares of his past life. He thinks it's just nightmares and tells Aerok... Only for aerok to be scared if Kloff finds out fully that it was real.
Kloff tried to marry Rapiel (the omega husband from the past) but loves Aerok to much to not think about him. Kloff being the abusive person he is, beats up these men that try to injure Aerok, making Kloff not qualified to marry Rapiel. Do the engagement gets cut off. 
A chain of events happens and Kloff ends up in a relationship with Aerok because Kloff became the financial advisor of Aerok and as they spend more time together, aerok's body starts changing into an omega naturally.
In the most recent chapters of the Manhwa, he's pregnant with their first child. They love each other but Kloff is still being plagued by nightmares.
So now go back to the first comment I put about the spoiler for future timeline.                                            

		
Can I get a overview of this please? Sad ending??