This is a difficult situation. Yes, you love her, but we all know 'you know' you love yourself more but trying to prove you love her is clouding your reasoning.
Don't try to make her trust you because it's a fake trust. One day, you'll definitely dump her but with pains. Be truthful to yourself. Her unique complexion and 'masterminded good attitude' is what is still keeping you. You won't agree to this, but it's the truth.
The lust (love) you have for her before knowing her status has caged you. You're just trying hard not to offend her. Walking away will make her hurt deeply and you can't stand to see her get hurt. It's an emotional thing, but one day, you'll realize everyone needs to carry their cross.
Don't carry someone else's cross - only encourage them to be strong and keep keeping on. Sadly, we may not be of help on how to make her trust you, because we don't also trust your decision in the first place. You're doing it out of pity and not wanting to see her depressed or commit suicide.
If you had learned the trade of a good-bad guy early in life, you wouldn't have been in this plight - you wouldn't have invested too much emotion. Now, it's difficult to disengage all in the name to keep a good image of your care and unconditional love. You're indirectly forcing yourself to live up to expectation on the kind of agape love you watch on religious movies.
If you do a proper research, you'll know she knew her status before now, but didn't tell you because she was scared to open up. She allowed you fall in love just to have someone by her side. She caused everything. She put you into this predicament. You're already entangled.
My advice is: Keep her as your best friend, encourage her, but move on. If you can't move on, then marry her at your own risks. Miracle may happen. With God, nothing is impossible. There are techniques to make people trust you, but in a case like this, it's not advisable. That's my advice.