Just wondering how to deal with them?

Around last year I met a girl at work. She had a bf (that was like 11 years older than her). I started liking her and people at work even thought we had something going on. I never made my move because she had a bf and I kept waiting for them to break up. They finally broke up after about three months of me knowing her and I was the rebound guy for about a month. She later abandoned our Valentine's plans and then called me a week after our plans apologizing and crying telling me "she never met someone who didn't want something from her before". Not going to lie, I was messed up for a good month after that. Later, I saw her on campus with the old bf again a month later and talked to her. Then we hung out a couple of times over the summer months. She would say her bf was too awkward because he was too old and I got along better with her friends. I even flew to the midwest and met her family. After summer, she had some issues with her boyfriend and then she met a new best friend. All three were friends I think for a little while and then something happened. We texted a couple of times throughout the fall and a little at the start of this year. Since about march, nothing. That girl she met that became her best friend for a few months is no longer friends with either of them. I knew that was a fake friendship then, especially when both of them would be on one line together and call me. It felt like a shallow friendship that wouldn't last.

I know in that time since the start of the year, she found another older boyfriend and then broke up. I really did not give a fuck, but I saw her walking down the street a couple of days ago and honked and waved at her as I drove by. The feels have been back since and I want to contact, but don't know if I should or not.

TL;DR: Met a super sexy girl at work almost 18 months ago. I became the rebound guy when she broke up with her bf. She got back with him around valentine's, but me and her kept in touch for the next few months. We then lost touch after she found a new older bf, broke up with him, went back to the ex, and is now single (I think). I saw her while driving and honked/waved as I drove past. Wondering if contacting is okay, or if I should still go no contact.