She going she also would die, the most reasonable thing was for her to no go, not her just going by herself.Yeah but here's the thing. If all of them went to Sasuke and started fighting him, they would've been dead. It doesn't matter how powerful Lee, Sakura, Kiba and Sai are, Sasuke would just murder them.
Taking Lee, Kiba and Sai were just to locate Naruto and Sasuke, which she shows when she asks where Sasuke is and then puts them to sleep.
She didnt wanted to involve them and it shows clearly on her conversation with Sai that she was planning to do something by herself.
Good?Sakura's plan was good, it failed but it was good. She went alone and tried to convince Sasuke that she wants to join him, so he can lower his guard and she kills him.
Through her actions she saved them. But sadly she failed in delivering the blow to Sasuke.
It relied on the fact her poison could work and her being capable of hitting Sasuke, there was no plan B, or C or D in case it fails.
It was pure kamikaze, her poison would not work on Sasuke as Kakashi stated because he worked on Orochimaru even she said during Naruto's training arc that Sasuke might used drugs.
Her plan had many failure points so it would not had worked.
The right thing was her going to tell Naruto what the k11 had decided and bring him back to the village but she didnt wanted to do it because from her POAL she didnt wanted to hurt Naruto anymore, in fact she wanted to take all the blame to herself, her mission since the begining if you haven't noticed it was for her to kill Sasuke and probably mgiht end dying too or even if she escaped make Naruto hate her.
She looked down at herself once again like many times of the manga and decided that she should end this whole team 7 thing by herself.