Driving Past NC

My ex and I broke up a little over 3 weeks ago. Right after we broke up I started the NC portion, three days into which he contacted me asking how I was doing. It took me 2 days to respond on because I didn’t know if I should break it or not to answer his question. In a bit of frustration I responded saying that I was doing well and thanked him for asking. The day after I thought I would text him and let him know that with everything that had happened, that while I enjoyed hearing from him I was just not in a place where I felt comfortable and that I would get back with him when I was. Of course he blew up at me just a bit and before you know it I was at his place crying and telling him that I wanted him back. Fast forward just a bit I was asked for my hand by my former-ex and I almost said yes but his horrible temper is cause for question. Ended up texting my ex, who I have been in constant contact with about the whole thing. He told me that he had found someone new but mentioned that he still thinks about me and reminisces about our happy memories. We made a pact that if neither of our current situations worked out, that we would explore being together again, on the stipulation that we can learn to trust eachother again. Having that conversation gave me the strength to again begin NC but with a stronger and different mindset. Now here is my dilemma.

We work right down the street from eachother and on any given day there is a high chance of him driving by me while I am walking to work. It has already happened several times since I started no contact and I always try to look happy and beautiful when he passes, all the time not texting to say hi or good morning. He doesn’t text me either. Fast forward to today when our passing almost brought me to tears. Today is my birthday. I did my makeup and all and of course it just happened to be raining and very windy. My umbrella was threatening to cave in and I just looked pitiful. Who do I see pull up in the lane closest to me but my ex. The last person I want to see me like this. As quickly as I could I pulled down the umbrella and attempted to pull of a glamour walk across the street. I was a little hurt that he didnt text me to wish me a happy birthday but even more hurt that he didnt text me to ask if I was ok. What should I be doing now as well as in the future passings during NC?