Sakura would probably be initially very angry. She has strong feelings for Sasuke, but kidnapping is a very extreme act. So she would likely fight back, using her medical ninjutsu skills and combat abilities to try and escape.
Sakura might be heartbroken. She's been in love with Sasuke for so long. She could initially go into denial, thinking it's just a temporary thing. Then she might get angry and vow to prove herself to Sasuke, perhaps by becoming an even stronger ninja.
She could be heartbroken. Sakura has always loved Sasuke deeply, so his leaving for Naruto would be a huge blow to her. She might initially be in denial, not believing that Sasuke would choose Naruto over her.
In some fanfictions, there are scenes where Sakura is in danger and Sasuke realizes just how much she means to him. For example, if Sakura is injured while protecting Sasuke, Sasuke's reaction of guilt and his newfound determination to always be by her side can be an extremely emotional part of the story.
Many fanfictions show Sasuke's sadness through his flashbacks. He constantly relives the day his clan was massacred, and these memories haunt him. Writers often use these flashbacks to highlight his internal pain, which affects his relationship with Sakura as he sometimes pushes her away because of it.
Sasuke would likely be initially shocked. He's a man who has been through a lot and is used to a life of solitude and danger. But then, a sense of protectiveness would kick in. He'd become more vigilant about the safety of Sakura and their unborn child. He might also start to think about how to be a better father than his own was, in some ways, trying to break the cycle of his family's past.
He could initially be in disbelief. However, as the reality sinks in, Sasuke would start to show his softer side. He might be more attentive to Sakura's needs, like making sure she eats well and rests. He would also start thinking about how to train their child to be a strong ninja in the future, while also wanting to give the child a more peaceful life than he had.
Well, a number of fans are divided. Some feel that the insults are a form of character assassination for Sasuke, as they view him as a more complex and redeemable character than one who would just randomly insult Sakura. Others, though, might see it as a way to explore the darker side of their relationship and how Sakura can grow from being insulted and become an even stronger character.
He could also be initially confused. Sasuke has known Sakura for a long time, and this unexpected act from her would leave him wondering about her motives. He may hold back his anger for a while to hear her out and understand why she did such a thing.