Romantic relationship with borderline

I was in an emotional relationship with a borderline person, and she completely consumed me psychologically and physically. After a while, I decided to stay away without telling her or explaining to her to avoid problems , but because her behavior towards me changed suddenly and without any reason, and because of this thing, I had the feeling that I was a bad person, even though I had not done anything wrong with her. With something, but this feeling is controlling me I am very tired. It is really difficult when you are honest in your words and actions, but they have no value or meaning for the person opposite. Idon’t know why she change with me i was always trying my best to support her😞.