So the doctors at Joslin want me on this Libre but it makes my skin break out and left a scar from the little needle being under skin. Has this happened to anyone else? I told them no, they keep harassing me to get on it.

Here’s a link to a forum discussion on the topic - some people have found creative ways to manage if not completely eliminate the irritation.
I’ve been using pumps and CGMs for a very long time and I do have some marks at some of my insertion sites but I would not call them scars. Irritation around the site may be manageable but I imagine scars on the skin mean there is scar tissue underneath as well, which could be problematic. Ideally you shouldn’t notice your transmitter. As valuable as a CGM is, if wearing it is bothersome they need to respect your wishes if you’re not able to find a solution.

I agree with @wadawabbit, she has great wisdom & experience. Historically, doctors are taught, “FIRST, do no harm.” If the Libre is harming your skin, the doctors need to go back & read rule 1.

I have sensitive skin. The other trick is to put a skin barrier down and shoot the Libre thru it. A brand I have seen is called IV3000 by Smith & Nephew.

Hope this helps. Let us know how things go. It is how we learn.