Good on you for having the nerves to ask the guy out in the first place!
Everyone gets rejected, and it feels bad and awkward and embarrassing, but if you pinned all your hopes on this one guy, you're bound to feel devastated, so my advice would be to find some more baskets to put your eggs into
Maybe give the online dating another try - having helped a single friend out recently with that, we learned that the different dating sites have different cultures... Some are little more than people looking for sex hookups, some are sort of more geared towards friendships, and of those in the middle, some are geared towards frivolous dating and some are geared towards finding life partners...
My advice there is to be open to things that are different... For example, when I did online dating, I was subconsciously really limiting myself from a lot of guys - men that fell into the "too short", "too tall", "too fair", etc categories. I ended up making a conscious decision to talk to guys on there even if they were any of those things. (Obviously, there were some things I would not compromise on because they were very important to me - things like smoking, religion, family, etc.) I found by widening my pool and talking to those guys, I ended up going out on some lovely dates... My friend went on a site that is a bit more serious about profiling members and finding well-suited long-term love matches.
...which brings me to my next point, which is something that I did when I tried online dating, and my friend did recently. That was having the mindset going into it that you're NOT looking for "the one". That places too much pressure and expectation on you and on the guy. My friend and my attitude was that dating is a skill, as is being in a relationship, and as with any skill, you need practice to get good at it. So both of us went from being totally clueless and insecure about dating through to becoming better at the whole online dating thing and going out on dates... Looking for a nice evening out and some pleasant company rather than "A Boyfriend", if that makes sense.
Incidentally, I met some lovely guys through online dating, but nothing really clicked and I didn't find a boyfriend that way, but I did have some nice experiences, saw some different restaurants, movies and theatre shows. My friend chatted with only a limited number of men on her site, went on a few dates with one before calling it off due to not feeling a spark with him, and then went out with a second one and has actually found "The One".
And to help your spirits, I'll tell you this - my friend was older than you and had never kissed a boy/man until she did this online dating thing, so I know from experience that you're not doomed to be single forever!