6 month ago, I attended a business meeting where I met this girl, we talked a bit but I had leave go so I forgot about her.

3 month later I went to a similar meeting, I was sitting somewhere with empty sits around. 

Guess who appears and comes siting next to me.. She was with a female colleague (hb3). This time I gamed her, within the limits of a buisiness meeting. There were clear IOIs despite saying she lived with her bf, so before leaving I took her number.

I contacted her a week later to go grab a drink together, she took a week to reply some vague answer not saying yes or no. I responded with a time and place, to which, one again she answered a week later saying she couldnt for this date and that we'd have a drink in june with her colleague (this was end of march). I stoped responding, next.

Today she sent me an invitation to grab that drink with her and the colleague.

I dont know what to do, ignore or go for the drink ?