I agree which makes it hard to believe she was in a hypnotic state. People in such a situation find it impossible to function away from their psychopath, it is like an addiction and all consuming. The fact that JM was able to attend college and get through her Teaching Practice makes it unlikely that she was a victim of such behavour by JB.
That's rather a generalisation and how one reacts to a psychopath depends on individual differences. Also, Julie didn't live with Jeremy so she was able to break away on a regular basis.
I don't think any of us can say why she didn't report Jeremy straight away - fact is she didn't but she was instrumental in his conviction and that's the main thing.