1. Alexis has acted desperate to get access to Scout and losing the case means losing access, so she'll be reluctant to throw the case....no matter how likely he abides by that, its her only chance.
2. The upcoming custody hearing would be moot if she's found guilty and I doubt this show will give up the opportunity to prolong this a little while longer. Imo she'll be acquitted and somehow this will come out during that hearing. Maybe she has a breakdown. So she doesn't go to prison, but does a few months at ferncliff then comes out and rebuilds her life.