In this case, why should she be completely separated from society?
I ask because of the apparent circumstance. If her crime is rooted in mental illness and having un-supervised access to her child, then the judge's order that she receive psychological treatment and be banned from unsupervised visits with the child seems to address the source of the trouble. As for taunting her ex, that's not really a crime - it just shows that she's fucked up and shouldn't be alone with her child, which was already addressed.
The cost of sending her to prison is very high and I don't believe it should be paid unless it's necessary. And "I hate what she did and want her to suffer" is insufficient to call a necessity. If you really want to spend tax dollars on her, send her to a mental hospital where she could come out a contributing member of society.