It's a little sad we're having this talk about childish behavior when you are (probably) a legal adult. I suppose many people blame biology and brain development and blah blah blah, but I won't accept that excuse.
Let me clarify something that defines your character and loses respect. Allow me to emphasize something you so ignorantly passed off as no big deal. I insist you try to understand how you hurt my friend.
Leading someone on means nothing to you, but it tears the rest of us apart. Leading someone on means telling them you like them, that you want to be there for them and that you can't wait to see them again. Leading someone on means asking if they're OK, making hypothetical future plans as if you'd follow through and listening to them when they need to vent. The problem arises the second you back out without warning out of fear of commitment–you become a liar.
Leading someone on doesn't have to be a bad thing. You could mean everything you say and then change your mind, but you need to use your words. Don't retreat, speak. You are never forced into a relationship. It has to be a two-way street, and you deserve happiness just like she does. But what you did was lie. She made time for you because she thought you wanted to spend it with her. She helped you when you asked for it because she thought one day you would return the favor. She thought of you when she saw a sign for your favorite Mexican restaurant because she thought you just might want to take her there one day.
So just to be clear: she did these things because you led her on. For the future, don't let a girl think you're ready for something that you're not. Communicate. The truth is, the burn of rejection earlier on is better than the burn of regretting lost time. Don't be selfish. Don't take the easy way out and just stop responding. Don't keep your fear of commitment to yourself.
I will always be here for my friend, and I'm here right now to pick up your mess, but you've done a lot of damage. I might not be able to make you change, but I'm hopeful that, in the very least, you can see what you've done wrong.
And if you're feeling sorry now–we both deserve more than an apology.