How to really stop obsessive thinking and to let go?

Hi, I have been broken up with my ExN for 15 months now and I am only trying to start NC now. The first 6 months after our break-up we were trying to reconcile and he would text me saying that he couldn't wait to see me, and then when he saw me, he would say "I'm trying so hard to get the feeling back". This was so hurtful and finally after a few months I just got so angry and told him never to contact me again.

Well, that didn't last for very long on my part. The following 6 months was me in a massive depression and suicidal. I was so confused and couldn't believe that the man that previously loved me so much, just didn't even care for me as a human being anymore. I tried to limit my contact to once/twice a month and every day that passed was really unbearable. My ExN told me to just "get on with it" and to remember all the reasons why I kicked him out in the first place (which he still does not take any responsibility for or has ever apologized for).

I only dated my ExN for a year and a half, but it was a romantic fairy tale and we were supposed to spend the rest of our lives together. I am Canadian and I moved to Scotland to find the man of my dreams at 32. I had such high hopes and when I met my ExN, it was like a dream come true. After a year together, we moved into a place of our own together and within six months I had kicked him out. It was like I was a shadow in my own home! I truly didn't REALLY exist!

Now, I have been going to counselling for 3 months and have tried to work on getting out of my depression. I am doing a lot better than before, but now I find that my obsessive thinking and deep down hopes that he could change if I showed him the way are continuously in my mind. How can I stop thinking this? How can I get over the hope that we could somehow magically live happily ever if he changes? I am 36 now and still in Scotland and any man that I meet, I keep comparing the feeling of when I first met my ExN. Nothing seems to feel as intense. How do we ever truly start letting go? Are there any helpful tips?

It doesn't help that my ExN and I have friends in common and we actually live on the same street! (yes, he moved out and moved into an apartment a few buildings over!) I am hoping to move to a different area soon, but I would really like to stop this obsessive thinking and to let go! Any tips would be greatly appreciated! Thank you!