I thought the thread title read "How a Girl Let Off".
Anyway two answers:
STUPID ONE: Tell her that Baghdatis is your little brother. Relationship GONE!!
SMART ONE: I'm going against the grain here. As someone who has dated my (now) fiancee for 11 years, and been engaged for 6 months, I'd say I'm pretty qualified to give you some advice.
If a female tells you she loves you, and she is being serious about it, unless you are too immature to handle a relationship, then why should it carry any bearing to how you feel about her? Obviously she likes you a great deal to say those 3 words, and has done so from her heart.
If the only issue is you being unable to reciprocate those 3 words, then tell her. BUT if you really do like her a lot, what's the problem?
Your mates may not think it's cool being in a long term relationship, but to be honest ask them where they are on a cold night, or when they need someone to have a heart to heart with, or when they want some action any time of the night do they warm their hands up.
Your reaction should be based on HOW YOU FEEL, not your reaction to WHAT SHE SAID.
Only you can answer and sort this one out. If she is serious in her words, and you dump her, she'll be shattered. Not to mention will you find someone as good as her when you've matured enough to want a relationship?
It's only 3 months I realise, but that 3 months could end up in 6, 12,18 months, or even 11 years like me.
I reckon sit down in a quiet place with some paper and a pen, and write down everything you like about her, every memory you've shared with her, and then everything you dislike about her.
Weigh up all those options with a level head and decide from there.
Ahh young love...