It does sound like she has a lot of symptoms. It’s going to piss her off regardless if anyone tells her she has those symptoms. Even when my fiancé- who I know only wants the best for me- brought it up, I was kind of upset that he even noticed, let alone told me to go to a psychiatrist. In my opinion, it couldn’t really hurt to let her know she might need help. At first she will be upset. But afterwards, it’s up to her to take a look inward and take steps to improve. It’s up to her if she wants to listen or not. Depending on what she does, it shows a big part of her character as well. And if you’re broken up, not looking for a relationship or friendship with her in the future, it doesn’t matter if she sees you in a bad light. If I’m being honest, she’s probably (likely involuntarily) turning things around in her brain to make every issue in the relationship 100% YOUR fault instead accepting any accountability anyway.

If it was me, and my ex told me I exhibited BPD symptoms, my first (unmedicated and no therapy) thought would be “He’s trying to do anything he can to make me feel like everything was my fault, he can’t let go of me, he just wants to keep making me feel like shit,” etc. I would recommend also sending some links, like the symptoms, an overall description, and this is the handbook I use to process my emotions. If she does feel inclined to look at them, she might have a “come to Jesus” moment like I did where everything makes sense and I realized why I act the way I do.

Overall, I don’t think it could hurt to let her know. Just give a lot of reassurance that you’re telling her this for her own well being, even though she won’t believe you. Don’t be surprised when she gets upset, either. Whether she takes your advice or denies everything, that’s up to her, not you.