Ok, so shes borderline. Thing is you know what her biggest weaknesses are and if you have spent enough time with her you know that she might see your statements as truth as long as you have not been working more on just making her feel good and focused on being honest and nice to her. If you then approach her and tell her how you feel honestly she will then regard you higher and might date you.

Secondly Imagine what it will do for her mental health.

There is a bit of a downside. if you like her enough be ready for a long tough road ahead. She will go from one extreme to the other but it is through you that she will have a common anchor to hold onto. With this in mind, Do not back out the second it seems too rough. If you do that, it might hurt her mentally worse than she is right now. So, you have to be willing to commit.

Can you see yourself with her a number of years down the road? If you can then go for it. Hook line and sinker her and never let go. The more trouble you two get into, is the more you have to love her. Even when things get to the worst, love her more and never let go. Love is a tough road and nobody is perfect, You saw through her imperfections and know what kind of a person she is deep down. Never forget that and you should have no insurmountable problems with her.