Don't mention it, and thank you for granting permission to me to reply to your question. I will try to do so concisely and with respect to you and the story that you've shared.

While I do not think that there is an objective "answer" to the question that you posed, you specifically stated "sadness." So, I will focus on sadness and your specific circumstances as you state them (as in how you are in the present while reflecting upon the past that consists of abuse, ex fiance and so forth.)

Although the feeling of sadness in the present for a person towards someone else, who abused that person in the past may seem strange, perhaps, the feeling is not strange because the person is empathetic to how ever a degree in the present (towards the other person,) the person appreciates in the present some aspect(s) of the past relationship and/or history with the person and/or the other, the person still has some emotional attachment (of how ever a degree, even if it is resignation about the past) towards that person, a combination of any of the three possibilities and/or other factors.

A relationship may be how ever complicated and/or complex (or not.) If abuse is an element of how ever a degree in the relationship, abuse causes (more) complication(s) and/or complexity to the relationship in general, even once the relationship is (for the most part or more) of the past and not of the present. (An example of such a claim is cognitive dissonance for possessing seemingly contradicting perspectives, emotions and so forth towards and/or about a person.)