Not currently, but I have in the past.
My suggestion to you would be to not let people affect how you do your job. Wherever you work, there will be difficult people, and they tend to gravitate toward people they think they can bully. Notice they never seem to pick on the confident nurses, right?
Honestly, so what if she is talking about you in report? Other nurses are smart, and are aware what she is up to. Do your job to the best of your ability, take constructive criticism, and don't let it affect you. If it were me, and I found out she was criticizing me behind my back, I would directly confront her each and every time, and let her know that if she has any issues with you she is to come directly to you. It might not do any good, but it will let her know that you are on to her and won't take crap from her.
As for the problem of the other nurses not taking care of your patients while you were dealing with 2 active labor patients (a complete handful...), I would go straight to the unit manager and decide how she wants this to be handled as a department. If it were me, I wouldn't just assume that someone was taking care of my patients, I would directly find the nurse who should be responsible, give her a short report and let her know that you are handing over care while you have labor patients. Then, chart "Report given to .....RN", naming the nurse by name. If this nurse doesn't take care of your (now her) patients while you are dealing with labor patients, it is her liability now.
I know this is difficult, but you shouldn't let one nurse affect your career. If you need OB experience to do your job better, by all means stay and get it. It sounds like your unit manager wants you to stay and is supportive, so why let difficult coworkers drive you off? Don't let them win. Be strong and confident, stand up for yourself, and document any exchanges with them so you can show your manager.