Ah, my ex was a medicated bi-polar...person. They'll say things, hurtful things sometimes, that they don't mean, they'll sometimes need encouragement, reassurance that they're not fat/ugly, etc. What worked really well was just keeping tabs on her like reminding her to bring a coat if its a windy day, making her lunch sometimes or what have you - make her feel important, loved, blah blah blah. Basically, treat them like a high maintenance house plant. Make sure she takes her meds too. My ex twitched a long in her sleep if she forgot but if you need your sleep, you could always try and hold her really tight - worked like a charm. Be open, be encouraging, don't be afraid to call her out on her bullcrap if its gets too much but do so in a mild and not so accusatory tone. Then hug her for about 8 seconds - this releases happy hormones in her brain and calms her the [censored] down. Avoiding excessive stimulants or depressants is a good idea too. Be stable, be a rock but don't sacrifice your own needs for her, you're not a martyr and she doesn't necessarily want an emotional tampon to hang around. On the whole, the experience wasn't too bad but don't let what they say get to you, I suppose.
Oh, for god's sake don't be sticking your dike in crazy. Most importantly, never promise crazy a baby and NEVER put a ring on it. You know, unless you have a death wish or you are a Zen mother [censored].