Funny you should think Theresa left Chloe to fend for herself. In that interview in SOD, JL said she was hoping fans wouldn't think she didn't care about Chloe, and she hoped she'd conveyed her concern over her enough. I think she did what she had to do. Should she have stayed put if Chloe wasn't let go also? No way, that would be suicide.
I haven't seen today's show yet, but why couldn't she have told Brady that Chloe was now a prisoner? Even if he couldn't help her (Victor hates Chloe and probably won't care -
), at least people would be aware of her predicament.