YOU ARE F* CRAZY DUDE.. DON'T EVER DO THAT AGAIN.. YOU ARE LUCKY TO BE ALIVE.. YOU DON'T EVEN NEED TO LIE ON THAT TRACK TO DIE...
Frankly.. it was a very BAD way to get to know her feelings and that is grossly WRONG. Thats emotional blackmail and it will only ruin your relationship in the future. Be frank to her and tell her everything on face rather than resorting to stuff like these. Believe me.. its not good.
Congratulations
OMFG.. don't use this line.. hardware become obsolete very soon... lolz...
Wait till I send this link to her

Honestly.. you've done it once.. don't ever do this again... it'll only create cracks in your long term relationship.
haha.. kahani mein twist

Ladki ka bhai.. send him over man.. go enjoy with the gal... we'll handle his bro
I don't know what else to say, but you echo my thoughts 100%. I don't even NEED to reply now, but still... here is my advice:
Emotional Blackmail is really really bad and evil. Besides, you don't even KNOW that she REALLY loves you. What if she just said that to make sure that you don't die ?
And one more thing: as a guy with a younger sister, I KNOW what responsibility I need to have
as an elder brother. My steps can be summed up as follows:
1. Check on that guy, in secret. Do a sherlock holmes thing and find out all you can about him.
2. Does he REALLY love her ? Is he just another prat or a pevert who is doing this just for showing off in front of his friends ? And most importantly, is he responsible and mature enough to handle such a relationship ? If any NO is there here, proceed to operation BREAK_THE_RELATIONSHIP.
3. If he is fine, then try to get friendly with him. Get to know him personally, and see if he makes a good friend. All this time, sis must not know you are doing what you are doing, nor should the guy know that you are his would-be GF's bro.
4. Once you are satisfied that he is decent, explore other factors, like society, taboos, etc and finally have a CHAT with sis. Explain her clearly that you know her story and that you are perfectly comfortable with that and you do not oppose the friendship. Tell her about the problems she might face, the issues with having a BF, etc.
5. When you are sure your sis understands you perfectly, while at the same time FEELS NO PRESSUREfrom your side and is perfectly comfortable talking to you, help her decide weather to keep the relationship or break it. If she decides to keep it, CONTINUE BEING A GOOD BRO. If she decides to break it, congratulations,MUCH LESS WORK FOR YOU.
many other guys I know do something similar. You might want to let things be for some time, but first
make sure that her bro is not an orthodox non-liberal non-understanding jerk.