Advice on how to handle someone who uses children as a manipulation tool?

Anyone out there had an ex that likes to do this? How did you deal with the conflict? How did you best manage communication so that the children weren't involved? How do you stop the constant phone calls and badgering without looking like you don't care for the children? This is the complicated situation my partner is in right now and she really loves to call and badger me too (as she prefers to talk to me because I'm female?) so I now feel like I'm involved in something that I shouldn't be! Oh, have suggested that she not involve me and this makes her really angry..... aaaaarrrgghh