I was recently in such a situation where one person was saying things and advising me not to support another. How I deal with it is When someone comes to me to talk about a person not themselves I disregard everything about the person that the "informer" tells me. Its not up to the "informer" to tell me about other people. I figure if the person of topic wants me to know these things that the "informer" is telling me about, that person will tell me thier self. I also let the "informer" know that I don't appreciate being pulled into a situation that does not involve me, then I cut off contact with the "informer" because if they are betraying the confidence of the person of topic then the odds are good to great that the "informer" is also betraying my information that I disclosed to him or her in confidence and trust.

Then I continue supporting and being there for the person of topic because for all I know the "informer" could have just been lashing out during anger and so against the person of topic so the validity of what was revieled to me could be true or it could be just lies.

Just because the "informer" is being unsupportive and partaking in the spreading of gossip does not mean I have to do the same.

Since my personal experience with the person of topic has shown nothing in the way of hurting others that person deserves my attention and support regardless of the information given to me from the "informer"