Well maybe she ignored your trying before because she still had a boyfriend and it just wouldn't be a right thing to do? You can't have a boyfriend and a friendship with a guy who potentially likes you, nothing good ever comes out of it.

Don't feel pressured and anxious, now that she is single it is a different story, go with the flow, be who you are and well, maybe ask her out? If she says yes - good for you, if she says no then maybe it only felt like there is a spark between you too.
good luck