First off I'd like to say that I've known this girl for about 4 years. We used to be friends but there was always sexual tension between us (nothing we ever talked about but was obvious) but nothing ever happened because either I had a girlfriend or she had a boyfriend. About 2 years ago I came forward but got rejected because she was in a relationship at the time. I really didn't have any game back then, so this was really awkward and humiliating. As a result we just stopped talking to each other for 2 years.
Recently she got back in touch with me on FB. She messaged me and sent me a request (after I removed her 2 years ago). I waited a day before accepting and replying and in the meantime a (girl) friend we have in common texted me asking why won't I accept her already, so it's pretty obvious this was important to her because they talked about it within hours. Also, I found out that she recently broke up with her (new) boyfriend.
The conversation on FB went something like this (translated):
Her: Wow back in touch after almost 3 years! Exciting... So how've you been?

[1 day pause]
Me: Heh no need to get all excited. How are you girl? What's new? [Added an old joke we had, making a little fun of her]
[2 hours pause]
Her: [Continuing our joke with some self humor...] Nothing special really, done working at [place we used to work] about 4 months ago, still trying to find myself.. What about you? [She then pastes a link of one of my pictures with some friends] So these are your new geek friends from engineering school?

[1 day pause]
Me: I see your turned into a comedian

Finished working at [same place], tried to find myself, found myself, and as you can see I started engineering school. And yeah, these are the kind of people you'll find there... But they're lucky to have me giving them bad influence, so they're improving

Now finished half of my degree, and working on a start-up I founded... Now tell me, what are you doing stalking my photos like that?
And then no reply for about 3 days while she's obviously active on FB. Now if I had to guess I'd say my mistake was being too cold or maybe negging her too much while I should've just asked her out on my 2nd reply, as going through my photos was an obvious IOI. The reason why I tried giving her a cold shoulder was because of our history. Just want her to know that I'm in a different place and forgot all about her, but I may have pushed it too far.
So, what do I do next? Was thinking maybe waiting a couple of days and then texting her again, not sure with what. Thanks for the help guys.