If you're a guy who's lucky enough to have a girl who would do anything for you, keep her around and treat her right. A strong woman with a good head on her shoulders, a plan for her future and a faithful mindset is not someone you should take for granted, ever. Today, an extremely large number of guys are so focused on a hookup or someone they can fool around with without any regard to their feelings. Unfortunately for the good girls that they end up hurting down the road, they halfheartedly wish for more and when they finally get that once in a lifetime girl of their dreams, they throw her away and keep the trash instead.
A girl who's worth it won't wait around more than a couple of times for you to make a decision on how you feel about her. If she really cares about you, she will make it clear. She might wait for you to figure things out in your life, but not in regards to your feelings for her. If she is full of life, she does not deserve to be half-loved. Treat her right or make room for someone who will. If she can take the good things and the extremely bad secrets about you and still somehow end up wanting you, keep her. The right girl isn't going to care about your past, she is going to care about your present and how you treat her during that present, so try your best to get it right.
Everyone makes mistakes, and if you make one with her, fix things. Fix things before it's too late and she settles for someone who doesn't make her feel the way you did only because he is willing to treat her with respect. Don't ignore her, don't use her. A girl worth loving may have walls around her heart, if she gives you the sledgehammer to knock them down, knock them down correctly, don't just leave her without an explanation as to why, you'll ruin her. If you aren't ready to give her the love she deserves from you, you need to tell her that. Don't just cut her off. The right girl will wait for you to work out your issues with your heart, but she won't wait if you don't tell her what's really going on in your mind.
If you let her go, you are a fool. This girl fell for you, she waited for you, she actually wanted you. She wanted you for everything you were and everything you weren't, she wanted the connection she feels with you and she wanted to be loved by you. Letting her go now would mean the end, because she would somehow move on from what she wanted most and try to find someone better. Tell her how you really feel, not what you think will keep her interested long enough until you decide when you're ready for her.
Let her in. Let her be the one to change you and grow together. Don't turn away the girl of a lifetime because you're scared. Love is supposed to be scary, falling is scary, but when the right person catches you, the end result is amazing.