Look you’re a lawyer so I’m probably not telling you anything you aren’t somewhat familiar with, but short of small claims which is usually more efficient (especially since you’re a lawyer), I agree with the advice of moving on rather than spending more than minimal effort trying to recoup your losses. 

I went through a lawsuit with a shitty ex business partner and I felt like my life was on hold while I was dealing with it. From that point on there have been many instances where I maybe felt slightly shorted in some sort of business deal but was happy to move on from it rather than battle it out.

Good for you pulling the trigger though...getting out of a relationship when you’re that far in is fucking hard and scary! It takes a lot of bravery to stick to your guns and see it through to completion. It’s never one conversation like you hope it will be...it’s resisting the perfect behavior after the fact that is so hard.