I'm big into the verse, "If it is possible, as much as it is up to you, be at peace with all men."-Romans 12:18. But there does come a time where people refuse to change, and their character is revealed over time. We can't change them. God can...but only if they are willing.
Excerpts from a book called, "Necessary Endings" by Dr. Henry Cloud:
"The strategy for foolish people is simple: Quit talking about the problem and clearly communicate that because talking is not helping, you are going to take steps to protect what is important to you, the mission, or other people. Give limits that stop the collateral damage of their refusal to change, and where appropriate, give consequences that will cause them to feel the pain of their choice to not listen.
The necessary ending that you have to initiate with people caught in their own foolishness is to end the pattern. You cannot control them or get them to change. What you can do is create an ending to the effects their refusal to take responsibility is having on you or others. By so doing, you have accomplished two things that nagging did not do. You have limited the effects of their behavior on you and others, thus quarantining their ownership disease from further infecting your life, the team, or the mission, and you may have done the one thing that can influence them to change. Talking will not help, but doing something that causes them to feel the consequences of their behavior may be what finally turns them around.
Do not hope for the evil persons to change. It could happen, and it does, but it does not happen by giving into them, reasoning with them, or giving them another chance to hurt you. It happens when they finally are subject to limits that force them to change.
Whereas you talk to wise people about problems and you talk to fools about consequences, do not talk to evil people at all, period."
I know the above doesn't typically apply to the minor disagreements we all have dealing with imperfect people like ourselves, who live in a fallen world, but there is a time to be strong enough to lay down some boundaries with people who are sapping the life out of you. Pruning is always a good thing to do to allow for further growth in plants as well as relationships.
As in everything, we should pray for wisdom in how to handle these relationships going forward. Yes, we are called to be longsuffering, but when some people are set out to destroy...you're not helping them in the long run by 'allowing' them to continue. You don't need to give everyone access to try and poison or even ruin your life...no need to hand them the key.