Is It Really Worth Reporting Someone For Obstruction Of Correspondence?

I just learned that for at least the last 3.5 years, someone else in my family that I have no contact with has been receiving and opening mail addressed to me. I am horrified, to say the least, because this mail is correspondence from doctors and insurance. This person has my medical information. Some of that medical information, specifically the information that lead to me discovering this, can put me in serious danger. I have safeguards in place already to prevent that, but I am horrified by this. Absolutely horrified. I have already contacted the doctor who sent the information to that particular insurance because I was told by them it would go through a different insurance, and I have contacted the insurance in question. Both of them told me there was nothing they could do. The doctor had to send it to that insurance first despite telling me it wouldn't be send to that one, and when I tried to contact the insurance company they told me they could only have one address on file, and that address has to be the policy holder.

This isn't the only crime she has committed, but the other one is well past its statute of limitations. I'm torn on what to do now. I want to report her. I really do. But there are major ramifications that would come from this beyond strictly legal ones. Reporting her would rip apart the last connection I have to my family. It could ruin her life and career (works directly with children, her other crime involves me as a child) even if nothing comes of it.

I guess what I'm asking is how seriously is this taken? Is it worth reporting? The ramifications are something I know I have to address on my own. They are there regardless of what I do. I am located in Wisconsin, US.