I think I inadvertently answered your question about healthy boundaries last week, when I replied to the question about guided imagery for co-dependency issues, which is a variation on the same theme.
All the tools you would need for repairing the integrity of your boundaries and helping you distinguish the perception of what is "self" vs. what is "not self", are in my answer about codependency, which is a common way that unhealthy boundaries can be expressed in a relationship.
So if you check out that answer, I think that will be your answer too.
Best of luck and thanks for the question.
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