Originally Posted by
hurtandangry 
Get a digital voice recorder and put it in your pocket every time you are around your ex.
Do this for your own protection not with the intention of catching them misbehaving.
Here is the one I use;
Amazon.com: Sony ICD-PX820 Digital Voice Recorder (Black): Electronics
The software it comes with will convert any recording to an MP3 that can be sent via the net to your lawyer.
Just an FYI, you might want to check with your lawyer about the laws concerning recording someone without their knowledge. It wouldn't do for you to have a recording you have made for your own protection used as a basis for a criminal charge or a civil suit against you!