I thought this very same thing earlier today.  That she is going to blame herself for Sasha's death.  But then I remembered that Sasha also mended the fence when Rosita wasn't looking and forced Rosita not to join her.  She went in guns blazing all by herself.  I do believe had Rosita been with her she either wouldn't have been caught, or together they would have come up with a whole other plan than taking a suicide pill.  

So although I do think she will go through some guilt....since she did get her there initially, I also believe that in the end....this was all Sasha.  God love her.  Lol 

And Rosita went to Sasha to ask for her help in the first place.  Based on that alone I'm sure she'll feel some blame for Sasha's ending.  Sasha would never have even been involved had Rosita not come to her. However, Rosita has an ego - what I mean here specifically is this...she doesn't tend to take a lot on to herself when shit hits the fan.  She simply reacts and wants vengeance.  Not to say she doesn't feel something, but it certainly doesn't affect her like it does the others.  We got a large insight into her psyche in that scene she shared w/Sasha as they were waiting to take out Negan sniper-style.  She lets things roll off her back and wants to keep going.

I'm hoping that now, seeing what's happened both of the times she's tried to take Negan out on her own (Eugene getting captured and then Sasha), she'd wise up and realize she can't do this Lone Ranger shit anymore, she has to work with the group.  So yes, I'm hoping she will respect how Sasha went out and finally fully immerse herself in the group, though I can't say for sure given her A-type personality...