I am getting into depression. Help!

Hi, I recently got break up with my love. She is married now. We were in live in relationship for the last 3.5 years. But she had to leave me because of her family issues. I am alone now and not able to come out of the zone. I know she won't come back but still can't believe that she has left me in one go. I don't have much friends and she was the only one around me. I have started to smoke a lot and now I have sleepless night. No one is around me and I have no one to talk. She is not talking to me any more and she is happy as her social media pics suggest. I know she won't be talking to me in the same manner as used to do it with me earliear. We shared everything. We were the best friends for the last 8 years. I am not able to move out her from my mind. My appetite has gone low and have become less interested in eating anything. We are in the same field as we are designers. Don't know how to tackle this problem. Things changed just in one day and my life has become miserable. help!😢