I have learned sometimes you really have to separate people from their actions. It sounds strange but often times we get offended (at least I have) because of how someone treated me not understanding that they had pure motives but they went about it the wrong way.
I have also learned that often people's actions towards you has nothing to do with you rather their own insecurities. They are broken in someway and your presence triggers their own pain and feelings of inadequacy. Even though you never felt anything negative towards them, their actions are a reflection of how they feel about themselves.
Learn to forgive. Yes you can still hold people accountable and rebuke them in love. Yes you can and in some cases should have a conversation about what will not happen should you be in my life in the future. Yet forgiveness is always the answer. Reestablishing communication may not always be